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Is a Diamond Really Forever?

You’ve probably seen ads on tv, in the mall, or on the radio advertising jewelry and saying that “a diamond is forever.” Is this saying true? Are diamonds special and rare? Or is it just marketing? 

Well, the answer is that it’s partially true. Any diamond that you can see could not form at the surface of earth because the conditions on Earth’s surface are not suitable for the formation of diamonds. At the surface of the Earth a diamond is metastable. This means that a diamond would not naturally form at the Earth’s surface, but if it arrives at the Earth’s surface it can exist there as if it were stable. The stable crystal form of carbon at the earth’s surface is graphite, the soft gray stuff in your pencil, not a diamond. 

How do diamonds form?

Diamonds form really deep in the Earth where there are very high pressures and temperatures. The only places that they form are at the base of continents. Continents are shaped kind of like icebergs, with more material on the bottom than on the top. It’s almost like a root to keep the continent balanced. This root area is where diamonds form naturally. As the diamond travels upward to the surface of the earth it will recrystallize to form graphite as the pressure and the temperature both decrease because it has entered the area where graphite is the stable form of carbon.

How do diamonds get to the surface?

So how does a diamond even get to the surface of the earth without recrystallizing to graphite? The answer is really, really fast. The diamonds that make it to the surface are blasted up quickly, at a rate somewhere around 30-50 miles per hour in order to not completely recrystallize or dissolve. If a diamond moves slower than that then it will no longer exist by the time it reaches the earth’s surface. 

Are diamonds rare?

No. Diamonds are not rare. They are fairly common, and are more common than many other minerals and gemstones. The main reason that we think diamonds are rare is because of the influence of diamond companies and their marketing strategies.

Before the DeBeers company pushed advertising on diamonds, many people used other, more colorful gemstones in their engagement rings. It was very common for engagement rings to be made with rubies or sapphires, which were the most popular gemstones for jewelry at the time.

Why are diamonds so popular?

The answer is really just marketing. Looking at a few different popular jewelry websites I see the following slogans about diamonds:

“A diamond is forever”

“A diamond is a girl’s best friend”

“Icon of modern love”

“You deserve the best”

“It’s your turn to shine”

Jewelry companies really want people to buy diamonds, so they have put a lot of effort into making diamonds seem like a necessity, and like the best gemstone you could put in a piece of jewelry.

What makes diamonds so special anyway?

Diamonds are really only special because of how we treat them. 

Yes, they do form under intense pressure deep in the earth, but so do many other gemstones.

Yes, they are sparkly, but so are other gemstones.

They do have a Mohs hardness of 10, which is the highest rating. This means that they will not be scratched by anything, so that does add to its value in jewelry, but there are other gemstones that have a hardness of 8 or 9 so they will also be very durable.

The only thing that makes diamonds special is that we love them so much and use them in a lot of our most special jewelry. That’s not a problem though! If you love diamonds then go ahead and buy them and wear them! I have diamonds on my wedding ring that I wear, so don’t think I’m saying diamonds are bad or that you shouldn’t wear them. They just aren’t as special or as rare as the diamond companies want you to think.

What is the difference between a natural diamond and a lab-grown diamond?

The only difference is really that natural diamonds form deep in the earth and lab-grown diamonds form in a lab. Other than that they are the same. They are made of the same material and have the same crystal structure. In fact, the only way to tell if a diamond is natural or lab-grown is to do some spectroscopic testing. This means that you would need to use a special piece of equipment to test how electromagnetic radiation interacts with the diamond. 

Other uses for diamonds

When you think of a diamond you probably think of a sparkling piece of jewelry. However, most diamonds are not gemstone quality, meaning they are not clear enough or sparkly enough or aren’t a good color. These diamonds, sometimes called industrial diamonds, are used to line saw blades, to test hardness, to make grinding wheels, and a lot of other things that usually have to do with the hardness of the diamond. Many of the industrial diamonds are lab-grown diamonds, however natural diamonds are also used as industrial diamonds. 

Conclusions

Diamonds are definitely beautiful, sparkly gemstones. They have uses both as gemstones and as an industrial material because of their hardness. Diamonds are not that rare or that special when compared to other gemstones, but we view them differently than other gems because of how successful the diamond companies have run their marketing campaigns. If you want to own a diamond for cheap you just need to look on Amazon! You can get a loose diamond for any budget there, from $7 up to thousands of dollars.

Sources:

Baird, Christopher S. December 17, 2013. “Why do Diamonds Last Forever?” Science Questions With Surprising Answers. http://wtamu.edu/~cbaird/sq/2013/12/17/why-do-diamonds-last-forever/

De Beers Group. “A Diamond is Forever: How the slogan of the century changed the diamond industry”https://www.debeersgroup.com/the-group/about-debeers-group/brands/a-diamond-is-forever

Ray, C. Claiborne. June 12, 2017. “Are Diamonds Really Forever?” The New York Times https://www.nytimes.com/2017/06/12/science/diamonds.html

Rosen, Seth I. 2019. “Are Diamonds Really Rare? Diamond Myths and Misconceptions”. International Gem Society.  https://www.gemsociety.org/article/are-diamonds-really-rare/

USGS. “Industrial Diamond Statistics and Information” National Minerals Information Center. https://www.usgs.gov/centers/nmic/industrial-diamond-statistics-and-information

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Where is Earth’s Water and How Does it Move?

Note for parents and educators: This article contains material that works with the following NGSS standards:

2-ESS2-3: Obtain information to identify where water is found on Earth and that it can be solid or liquid.
5-ESS2-2: Describe and graph the amounts of salt water and fresh water in various reservoirs to provide evidence about the distribution of water on Earth.
MS-ESS2-4: Develop a model to describe the cycling of water through Earth’s systems driven by energy from the sun and the force of gravity.

Have you ever wondered where the water you drink comes from? You have probably noticed that water from different cities tastes different. I liked the water from my grandparents’ house in Highland, Utah the best out of any tap water I’ve had. I lived not too far away, in Provo, Utah while I was going to college. The water there didn’t taste as good. That water still tasted better than the water at my parents’ home in Northern Virginia, which often tasted like chlorine. Why does all the water taste different?

Where on Earth is all the water?

It is important to understand where the water on Earth is located if we want to understand where our water comes from. If you have seen any picture of the Earth you have probably noticed that there is more water on the Earth than there is land.

In this picture of the Earth we can see that the majority of its surface is covered by water. Photo from pexels.com, CC0 license

Water covers 71% of the Earth’s surface, and as you can see when you look at the above image of the Earth, the oceans hold most of that water. That’s where 96-97% of all the water on Earth is. The next largest reservoir for Earth’s water is ice. This includes the Earth’s ice caps, glaciers, and snow at the top of mountains. Ice makes up 2% of Earth’s total water.

The salty ocean water and the water frozen in ice aren’t available for us to drink. That makes almost 99% of all water unavailable for our use unless we develop an easy and cheap way to extract fresh water from the ocean. For now it is cheaper and easier to use other sources of water. Most of the water that we use for drinking water comes from the ground. Fresh groundwater is less than 1% of all the total water on Earth, but that is what we mainly use for agriculture and consumption. Many people think of lakes or rivers when they think of fresh water. However, you will find less than 0.05% of all Earth’s water in one of these locations.

How does Earth’s water move?

I’m sure that you have experienced rain or hail or snow at some point in your life. Rain, hail, and snow are all examples of precipitation, one of the ways that water can move around the Earth. Here are some of the other ways:

  1. Evaporation
  2. Transpiration
  3. Condensation
  4. Precipitation
  5. Groundwater
  6. Runoff

Evaporation

Earth’s seasons help the water move around. The Earth has a tilted axis, so half of it is closer to the sun than the other half is for 6 months of the year. The months of October through April are colder in the northern hemisphere and warmer in the southern hemisphere. The months of April through October are warmer in the northern hemisphere and colder in the southern hemisphere. Evaporation is easier during warm periods of time, when water on the ground, in the ocean, in rivers, and in lakes gets heated and allows some small particles of water to enter the air. These particles are small enough that we cannot see them, but sometimes we can feel them. Some days are more humid than others and on those days you feel sweatier and can feel the water in the air. 

Transpiration

Transpiration is a word used for the water that is released by plants. We, as humans, drink water and eat foods that contain water. We also release water through sweat, urination, and as water vapor when we breathe. Plants also drink and then release water. Plants release water in vapor form, through tiny holes in their leaves. This is similar to us breathing!

Some water cycle diagrams combine the processes of evaporation and transpiration. This is called evapotranspiration, and it is the water that has evaporated from the surface of the earth plus the water released by plants through transpiration.

Condensation

Water in the air can condense, meaning the particles come together and the water is visible again. This depends on the temperature of the air, the concentration of water particles in the air, or both. Cold air cannot hold as much water as hot air can. An example of condensation because of temperature is when the air cools overnight and there is dew on the ground in the morning. This can also happen when you leave a glass of ice water on the table and water drops condense on the outside of the glass. We can also see condensation high in the sky. Water particles condense and join together in big groups to form clouds.

Moisture in the air condenses and forms dew drops on these blades of grass.Photo from pexels.com, CC0 license.

Precipitation

We know that clouds form by condensed water particles joining together. But what happens when too many water particles are in a cloud? When a cloud gets too heavy from having a lot of water particles in it, then it will cause precipitation. Precipitation is any form of water falling from the sky, such as rain, snow, or hail. When this water hits the ground, some of the it will go into the ground to join the groundwater. Some of the water will become runoff, which means that it will run along the surface of the earth until it gathers in a river, a lake, or the ocean. The water that is runoff on the surface of the Earth can also evaporate again before it reaches any of those locations.

Groundwater

Water that is stored in the ground is called groundwater. The chart earlier in this article showed us that 1.69% of Earth’s total water, and 30.1% of Earth’s total freshwater is stored in the ground. Many people around the world get their drinking water from groundwater. Groundwater moves around, just like the water on the surface of the Earth. As the groundwater moves, it can pick up minerals from the rocks or soil through which it is traveling. This is what causes tap water to taste different in different cities around the world.

Runoff

You have probably seen water rushing across the ground when it rains a lot. This water is runoff. Not all of the rain or snow water can be absorbed into the ground to join the groundwater, so some of it runs along the surface of the Earth until it finds a lake, stream, or ocean to join.

Sources:
Brigham Young University College of Physical and Mathematical Sciences, 2012, Physical Science Foundations, 4th ed., BYU Academic Publishing

Rutledge, K. et al, 2011, “Condensation”, National Geographic Resource Library, https://www.nationalgeographic.org/encyclopedia/condensation/

USGS, “The Water Cycle for Adults and Advanced Students”, Water Science School, https://www.usgs.gov/special-topic/water-science-school/science/water-cycle-adults-and-advanced-students?qt-science_center_objects=0#qt-science_center_objects

USGS, “Where is Earth’s Water?”, Water Science School, https://water.usgs.gov/edu/earthhowmuch.html

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Understanding Earthquake Magnitude

I lived in San Diego, California from the time I was 3 until I was 13. While I was there I felt a few earthquakes, but most of them were pretty small. The most memorable earthquake happened probably around 2003 or so. I was at a friend’s house and we were eating a snack at the table. Suddenly there was a rumbling sound and the glasses and plates on the table started shaking around, so we quickly rushed to the doorframe to wait until the earthquake was over. Earthquakes don’t last very long, so it was over quickly. Where I was, nothing got damaged or broken in that earthquake, but it was strong enough to be memorable.

Because I lived in an earthquake-prone area in my childhood I was curious about earthquake magnitude and what it really meant when an earthquake was a 4.2 or a 6.6. I also wondered, why are earthquakes sometimes reported with a magnitude of 5.4 by one news source, but 5.6 by another? When I see an earthquake magnitude listed it’s normally a number, but sometimes it’s a Roman numeral, do those mean something different? If you are curious about any of these things, just like I was, then you can get the answers here.

Earthquake article logo

What is earthquake magnitude?

In 1935 a man named C. F. Richter made up a way of measuring earthquakes based on how much energy each earthquake releases. If the name Richter sounds familiar it’s because the system he made is called the Richter scale and is commonly used to measure earthquake magnitude. The energy from the earthquake moves through the ground as seismic waves. The size of the very first seismic wave to arrive is used in the calculations to determine magnitude. Something interesting about magnitude is that it is on a logarithmic scale.  This means that as the magnitude gets a little bit bigger the size of the earthquake gets a lot bigger. I made some graphs to show this relationship.

This graph shows how an exponential relationship looks on a regular scale graph. As the numbers on the bottom, or the x-axis, get a little big bigger, the numbers on the side, or the y-axis, get much bigger very quickly. For earthquakes the x-axis would be the magnitude of the earthquake and the y-axis would be a unitless representation of the size of the earthquake.

 

This graph shows the same graph as the previous one, but now the y-axis is a logarithmic scale, making it easier to see just how much the y value changes with each x value increase.

 

A logarithmic scale means that a magnitude 2 earthquake is not the same as a magnitude 1 + another magnitude 1. Instead a magnitude 2 is as big as 10 magnitude 1 earthquakes

A magnitude 2 is also as strong as nearly 32 magnitude 1 earthquakes happening at the same time.

The difference between bigger and stronger.

A magnitude 2 earthquake is 10 times bigger than a magnitude 1 earthquake. This means that the amplitude, or height, of the first seismic wave from the magnitude 2 earthquake is 10 times taller than the amplitude of the first seismic wave from the magnitude 1 earthquake. A magnitude 2 earthquake is nearly 32 times stronger than a magnitude 1 earthquake. Strength measures the amount of energy that is released. So a magnitude 2 earthquake releases the same amount of energy as nearly 32 magnitude 1 earthquakes happening at the same time.

The United States Geological Survey (USGS) has a “How Much Bigger…?” Calculator that you can use here to see just how much bigger a 6.3 is than a 5.4, or whatever other numbers you’d like. In my geophysics class we had to do all those calculations ourselves, but this handy calculator is much easier!

To really understand the differences in magnitude I’ll take two earthquakes that most people are very familiar with and compare them. Many people remember the 1994 Northridge Earthquake that happened in California because it was very destructive. Another very destructive earthquake was the 2004 Indian Ocean Earthquake, which also caused a large, destructive tsunami.

The 1994 Northridge Earthquake was a magnitude 6.7 earthquake.

The 2004 Indian Ocean Earthquake was a magnitude 9.3 earthquake.

Here are the results from the USGS “How Much Bigger…?” Calculator:

Famous Earthquake comparison

So the first seismic wave to arrive at the 2004 Indian Ocean Earthquake was 398 times taller than the first seismic wave to arrive at the 1994 Northridge Earthquake! The Indian Ocean Earthquake also released the same amount of energy as if almost 8,000 of the Northridge Earthquakes were happening at the same time in the same place!

Calculating Magnitude

Sometimes you will see different magnitudes reported for the same earthquake. Here are some examples of that using the 2004 Indian Ocean Earthquake. I found some news articles about the earthquake and took a screenshot of what they say the magnitude is. The full article is also linked for each example. 

The Guardian says it was a magnitude 8.9, 

The Guardian magnitude

the New York Times says it was a magnitude 9.0,

New York Times magnitude

Earth Magazine says it was a magnitude 9.2,

Earth Magazine magnitude

and BBC says it was a magnitude 8.9.

BBC magnitude

So what’s up with these numbers?

Are these news sources going crazy? Did they not bother to do the calculations right? Are they really just guessing? The answer to all of these questions is no. This doesn’t mean that one person calculated it wrong and the other person calculated it right. There are actually a few different ways to calculate different types of magnitude and some news sources will say which calculation they used. Here is a screenshot from the Wikipedia page “List of 21st-century earthquakes”

Magnitude types

You can see here that in the comments next to the magnitude column there a comment with either Mw or Mb. Those letters are identifying which magnitude calculation was used. Mb is a calculation of magnitude based on the seismic body waves, which is one of the types of waves that allow the energy released during the earthquake to travel through the earth. Mw is the moment magnitude, which is calculated using the seismic moment, which is a function of the area of a fault and how much the earth moved along the fault. There is another measure of magnitude, Ms, which is calculated using the seismic surface waves, another type of wave that allows the seismic energy to move through the earth. Ms is not commonly used, Mb is sometimes used, and Mw is the most common. Each different method of calculating the magnitude can give a slightly different answer. This is why you might see two different news sources reporting two different magnitudes for the same earthquake. 

The Mercalli Scale

There is another way of representing how big an earthquake is, called the Mercalli scale. The Mercalli scale is a subjective scale, so it cannot be calculated mathematically like the Richter scale is. The Mercalli scale ranges from 1-12 and is usually represented by Roman numerals. Each number is associated with a certain amount of shaking and destruction. This means that an earthquake in an area that is prepared for earthquakes will rank lower on the Mercalli scale than the same earthquake in an area that is not prepared for earthquakes.

Here we can see a bridge that was destroyed in an earthquake that happened in San Fernando, California in February, 1971. Photo from USGS and is in the public domain.

 

Here is an idea of what each number in the Mercalli scale represents

I – Most people won’t notice this earthquake; there is only a little bit of shaking.
II – Most people won’t notice this earthquake either. If you’re lucky and happen to be sitting very still at the top of a very tall building, doing nothing you may notice some very gentle swaying but may not recognize it as an earthquake.
III – Most people in a building will feel some shaking or swaying but may not recognize it as an earthquake. The sensation is a slight shaking or rumbling similar to when a large truck, like the garbage truck, passes by your house.
IV – You will notice shaking, and something small like a cup or a plate might rattle on the table. If you are asleep you might wake up even though you may not know why you woke up. Even if you haven’t experienced an earthquake before you would probably recognize this as an earthquake.
V – You would have to be doing something very active to not notice this earthquake. The shaking is strong enough to break a few windows or knock plates off of shelves.
VI – You definitely feel this earthquake and furniture will slide or shake around. The shaking could break small sections of walls. This earthquake will cause a small amount of damage, but nothing major.
VII – Buildings built to withstand earthquakes will not have noticeable damage. Older buildings or buildings not built to withstand earthquakes will have more significant damage and some chimneys may break.
VIII – Columns on buildings crack or fall, chimneys break. Partial collapse on most buildings. Only specially designed buildings will have a small amount of damage. Other buildings will have significant damage.
IX – Buildings collapse and shift off of their foundations. Even specially designed buildings will have a significant amount of damage.
X – Brick buildings destroyed. Most wood-frame buildings destroyed.
XI – Mostly all buildings are flattened. Bridges are broken.
XII – This is like an end-of-the-world earthquake, which causes total damage. Nothing is left standing. Everything is broken and collapsed and there is a large death toll.

The Mercalli scale is not used as frequently as the Richter scale, mostly because it is so subjective. How an earthquake ranks on the Mercalli scale really depends on where it hits and how prepared that area is for an earthquake. Here is a simple infographic to show the differences between the Richter scale and the Mercalli scale.

earthquakes infographic

Sources:

Fowler, C. M. R., 2005, The Solid Earth: An Introduction to Global Geophysics, 2nded., Cambridge University Press

USGS, Earthquake Hazards Program, https://earthquake.usgs.gov/earthquakes/