how gem stones get there color

How Gemstones Get Their Colors Color is the most important characteristic of gemstones, though in the case of many diamonds it is the absence of color which is most important. But why do the different gemstones have different colors? What's responsible for the variation in color? Color is produced by the way a gemstone absorbs light. Light is an electromagnetic vibration at certain wavelengths, but the human eye can only perceive wavelengths between 380 and 750 nm. This is the field of the visible color spectrum: red, orange, yellow, green, blue and violet. If all the different wavelengths of light pass through a gemstone, it will appear colorless. On the other hand, if the gem material absorbs all light, it will be appear black. But if a stone absorbs all wavelengths except those in the red part of the spectrum, the gem will appear red. There are several different reasons why the various gemstone varieties absorb light differently. Some gemstones are said to be idiochromatic or "self-colored", meaning that they absorb certain wavelengths of light due to characteristics of their chemical structure. Peridot, which contains iron, is an example of an idiochromatic gemstone. However, idiochromatic gemstones are rare. Most gemstones are allochromatic, meaning that they are colored by impurities or trace elements in their crystal structure. For example, pure corundum is colorless. But corundum is typically red when traces of chromium are present; and blue when there are traces of titanium. We call the former ruby, and the latter sapphire. The most common trace elements in gemstones are beryllium (emerald), chromium (emerald, jade, chrome tourmaline, ruby and topaz), copper (paraiba tourmaline, turquoise, malachite), iron (yellow sapphire, aquamarine, green tourmaline, chrysoberyl, citrine, jade), lithium (green or pink tourmaline), manganese (pink tourmaline, morganite, kunzite, spessartite garnet), sulfur (lapis lazuli), titanium (sapphire) and vanadium (emerald, alexandrite, color-change sapphire). One thing you will notice from this list is that the relation between a chemical impurity and a gemstone color is not a simple one. In some cases, a similar color can result from different trace elements -- the green of an emerald can be the result of chromium or vanadium (or both). In other cases, a single trace element can produce different colors in different gem varieties. Thus chromium will produce a green color in emerald, but produce a red color in corundum. This is because there is a complex relation between the gem's crystal structure and the trace elements. This short survey would not be complete without mentioning another important way in which gemstones acquire color -- through human intervention in the form of gem treatments. Heat treatment, for example, is often used to change the chemical state of an impurity to deepen or lighten color, reduce a certain hue (such as the green tone in aquamarine), or improve clarity.

First Published: March-11-2008

How Gemstones Get Their Colors
Color is the most important characteristic of gemstones, though in the case of many diamonds it is the absence of color which is most important. But why do the different gemstones have different colors? What's responsible for the variation in color?
Color is produced by the way a gemstone absorbs light. Light is an electromagnetic vibration at certain wavelengths, but the human eye can only perceive wavelengths between 380 and 750 nm. This is the field of the visible color spectrum: red, orange, yellow, green, blue and violet.
If all the different wavelengths of light pass through a gemstone, it will appear colorless. On the other hand, if the gem material absorbs all light, it will be appear black. But if a stone absorbs all wavelengths except those in the red part of the spectrum, the gem will appear red.
There are several different reasons why the various gemstone varieties absorb light differently. Some gemstones are said to be idiochromatic or "self-colored", meaning that they absorb certain wavelengths of light due to characteristics of their chemical structure. Peridot, which contains iron, is an example of an idiochromatic gemstone.
However, idiochromatic gemstones are rare. Most gemstones are allochromatic, meaning that they are colored by impurities or trace elements in their crystal structure. For example, pure corundum is colorless. But corundum is typically red when traces of chromium are present; and blue when there are traces of titanium. We call the former ruby, and the latter sapphire.
The most common trace elements in gemstones are beryllium (emerald), chromium (emerald, jade, chrome tourmaline, ruby and topaz), copper (paraiba tourmaline, turquoise, malachite), iron (yellow sapphire, aquamarine, green tourmaline, chrysoberyl, citrine, jade), lithium (green or pink tourmaline), manganese (pink tourmaline, morganite, kunzite, spessartite garnet), sulfur (lapis lazuli), titanium (sapphire) and vanadium (emerald, alexandrite, color-change sapphire).
One thing you will notice from this list is that the relation between a chemical impurity and a gemstone color is not a simple one. In some cases, a similar color can result from different trace elements -- the green of an emerald can be the result of chromium or vanadium (or both). In other cases, a single trace element can produce different colors in different gem varieties. Thus chromium will produce a green color in emerald, but produce a red color in corundum. This is because there is a complex relation between the gem's crystal structure and the trace elements.
This short survey would not be complete without mentioning another important way in which gemstones acquire color -- through human intervention in the form of gem treatments. Heat treatment, for example, is often used to change the chemical state of an impurity to

why do crystals have different shapes and sizes?

how do crystals get there color

Crystals come in all shapes, sizes and colors. The variation in color is generally caused by the chemical elements involved while the crystal is being formed.

 

Quartz

Most crystals are colored quartz. Quartz changes colors because of the chemicals found in the surrounding environment when it is forming.

Chemicals

Different colors are created by different chemicals. Amethyst for example has iron deposits built into its crystalline structure giving it a purple cast. Crystals with sulfur built into their structure have a yellow cast.

Growth Imperfections

Some coloration, like that found in smoky quartz, are the result of growth imperfections. These imperfections effect the way the crystal reflects light, and so change the appearance of coloration.

Light

Part of the color we see when looking at a crystal is light. When light enters a crystal its spectrum is broken apart, and part of it is absorbed while other parts are reflected. This reflection and absorption changes the apparent color of the crystal.

Cutting

The shape of a gem is often altered, and facets added, to enhance the color of the crystal. The planes of the cut crystal alter the way in which it interacts with light, and so alters the color.

how to grow great crystals

 are general instructions for growing crystals that you can use for most crystal recipes. You can find the recipes and information on crystal structures in the Growing Crystals section. Here are the basics, to get you started and help you troubleshoot problems:
What Are Crystals?
Crystals are structures that are formed from a regular repeated pattern of connected atoms or molecules. Crystals grow by a process termed nucleation. During nucleation, the atoms or molecules that will crystallize (solute) are dissolved into their individual units in a solvent. The solute particles contact each other and connect with each other. This subunit is larger than an individual particle, so more particles will contact and connect with it. Eventually, this crystal nucleus becomes large enough that it falls out of solution (crystallizes). Other solute molecules will continue to attach to the surface of the crystal, causing it to grow until a balance or equilibrium is reached between the solute molecules in the crystal and those that remain in the solution.
The Basic Technique

• Make a saturated solution.
• Start a garden or grow a seed crystal.
• Continue growth.

In order to grow a crystal, you need to make a solution which maximizes the chances for the solute particles to come together and form a nucleus, which will grow into your crystal. This means you will want a concentrated solution with as much solute as you can dissolve (saturated solution). Sometimes nucleation can occur simply through the interactions between the solute particles in the solution (called unassisted nucleation), but sometimes it's better to provided a sort of meeting place for solute particles to aggregate (assisted nucleation). A rough surface tends to be more attractive for nucleation than a smooth surface. As an example, a crystal is more likely to start forming on a rough piece of string than on the smooth side of a glass.
Make a Saturated Solution
It's best to start your crystals with a saturated solution. A more dilute solution will become saturated as the air evaporates some liquid, but evaporation takes time (days, weeks). You will get your crystals more quickly if the solution is saturated to begin with. Also, there may come a time when you need to add more liquid to your crystal solution. If your solution is anything but saturated, then it will undo your work and actually dissolve your crystals! Make a saturated solution by adding your crystal solute (e.g., alum, sugar, salt) to the solvent (usually water, although some recipes may call for other solvents). Stirring the mix will help to dissolve the solute. Sometimes you may want to apply heat to help the solute dissolve. You can use boiling water or sometimes even heat the solution on the stove, over a burner, or in a microwave.
Growing a Crystal Garden or 'Geode'
If you just want to grow a mass of crystals or a crystal garden, you can pour your saturated solution over a substrate (rocks, brick, sponge), cover the setup with a paper towel or coffee filter to keep out dust, and allow the liquid to slowly evaporate.
Growing a Seed Crystal
On the other hand, if you are trying to grow a larger single crystal, you will need to obtain a seed crystal. One method of getting a seed crystal is to pour a small amount of your saturated solution onto a plate, let the drop evaporate, and scrape the crystals formed on the bottom to use as seeds. Another method is to pour saturated solution into a very smooth container (like a glass jar) and dangle a rough object (like a piece of string) into the liquid. Small crystals will start to grow on the string, which can be used as seed crystals.
Crystal Growth and Housekeeping
If your seed crystal is on a string, pour the liquid into a clean container (otherwise crystals will eventually grow on the glass and compete with your crystal), suspend the string in the liquid, cover the container with a paper towel or coffee filter (don't seal it with a lid!), and continue to grow your crystal. Pour the liquid into a clean container whenever you see crystals growing on the container.
If you selected a seed from a plate, tie it onto a nylon fishing line (too smooth to be attractive to crystals, so your seed can grow without competition), suspend the crystal in a clean container with saturated solution, and grow your crystal the same way as with seeds that were originally on a string.
Keeping Your Treasures
Crystals that were made from a water (aqueous) solution will dissolve somewhat in humid air. Keep your crystal beautiful by storing it in a dry, closed container. You may wish to wrap it in paper to keep it dry and prevent dust from accumulating on it. Certain crystals can be protected by being sealed with an acrylic coating (like Future floor polish), although applying the acrylic will dissolve the outermost layer of the crystal.

 

how are diamonds formed

How and where are diamonds formed?
Diamonds form between 120-200 kms or 75-120 miles below the earth's surface. According to geologists the first delivery of diamonds was somewhere around 2.5 billion years ago and the most recent was 45 million years ago. That is a long time, my friend! According to science , the carbon that makes diamonds, comes from the melting of pre-existing rocks in the Earth's upper mantle. There is an abundance of carbon atoms in the mantle. Temperature changes in the upper mantle forces the carbon atoms to go deeper where it melts and finally becomes new rock, when the temperature reduces. If other conditions like pressure and chemistry is right then the carbon atoms in the melting crustal rock bond to build diamond crystals.
There is no guarantee that these carbon atoms will turn into diamonds. If the temperature rises or the pressure drops then the diamond crystals may melt partially or totally dissolve. Even if they do form, it takes thousands of years for those diamonds to come anywhere near the surface.
Are you guys with me? A lot of information, huh! Let's continue!
Diamond's journey to the surface?
Diamond deposits are called Kimberlite Pipes or Blue Ground. These are also called Primary Mines. On the other hand, diamonds are also found at river beds. These are Alluvial Deposits.

So you see that Mother Nature has to toil for millions of years to make a diamond. When you own a piece of diamond, you own something which is a legend in the making. It has not been made in a factory just the other day. A diamond comes from the bosom of the earth. More interestingly not all the diamonds mined are made into jewelry. Only one fourth quantity that is mined is made into jewelry. Every 100 tons of mud produces one carat of a diamond. And might I add, this one carat is not one stone! It could be anything from 0.005 ct to 1 ct..
Would you like to see how a rough diamond looks? This image on your right is an example of a rough diamond. This particular one is called a 'Glassy'. Glassy is a rough diamond that comes out clean from the mines and does not require polishing. It is very rare to get a glassy. Diamonds come in different rough shapes. This one is an octahedron. The next time you look at your diamond, think about the amount of time, energy and resources have gone into making that one. Something for you to ponder about!!!

how do crystals grow in caves

• 

  Rock

range of shapes and sizes, from crystals visible only under a microscope to towering giant crystals formed over thousands of years in specialized conditions. Crystals develop through a complex series of stages, developing around a nucleus, gathering material and growing larger the longer they are left in a crystal-conducive environment

Crystals can develop in a vast

Nucleation

• All crystals form as a result of two processes, called "nucleation" and "crystal growth," in a "supersaturated" liquid solution (a liquid with something dissolved in it; for example, salt). This will occur in a cave if it is flooded with one of these liquid solutions for as long as a hundred thousand years or more. The first step, nucleation, occurs when groups of molecules floating in a solution begin to stick together in stable clusters. Whether a cluster of molecules becomes stable depends on many factors within the solution, including temperature and whether it is "supersaturated."

Supersaturation

• Supersaturation occurs when the solution contains more of the dissolving material than it can dissolve. For example, if you continue stirring sugar into a cup of coffee, the liquid will eventually become "saturated" and unable to dissolve any more sugar. Supersaturation would occur if you added yet more sugar until particles were floating in the coffee, unable to be dissolved.

Crystal Growth

 The way the molecules stick together during nucleation plays a role in defining the eventual shape of the crystal. Crystal growth occurs when the stable clusters in the solution achieve critical size (the minimum dimensions the crystal molecules must reach to continue growth without disintegrating). Nucleation continues as crystal growth develops beyond critical size and is driven by supersaturation, providing additional molecules to stick to the nucleus of the fledgling crystal. Depending on conditions within the solution, nucleation or crystal growth may be predominant over the other and result in different-size crystals. Crystal growth or nucleation continues until supersaturation is ended or the cave dries completely.

Different Types of Crystal

• Many different types of solution have the ability to produce different types of crystal. For example, salt crystals occur when salt is dissolved in water and dried, but other materials dissolved in a solution have the ability to form crystals, too. Gallium and halite are other materials known to crystallize.

Making Your Own Crystals

• You can easily form salt crystals at

how do crystals form

Question:  How do crystals form? ---Dave

Answer:
Crystals usually form from molten rock as the molten
rock gradually cools.  If the molten rock
cools very rapidly, then either small crystals
form or no crystals form.  An example of this
is when lava is ejected from a volcano.  If
molten rock cools slowly, then large crystals
can form.  This happens usually when the molten
material is very deep in the Earth.  Examples
of these types of crystals are diamonds, emeralds,
rubies, etc.Crystals can also form when water evaporates.
For example, salt crystals (sodium chloride) form
when salt water evaporates.

The smooth faces of crystals are caused by
a regular internal arrangement of atoms.
-Grant