There is an abundance of multi-colored gemstones available on the market. There are gems to suit individual tastes, artistic requirements, and budgetary restraints. Some of the more popular, colored stones are rubies (red), sapphires (blue), emeralds (green), and topaz (yellow). In their most basic form, the majority of gemstones are clear/colorless. The nature of the visible light spectrum, coupled with impurities and/or inclusions, determines the color of each gemstone. Certain minerals will absorb parts of the light spectrum, but not others, and this results in a specific color being "reflected back" to observers' eyes.
Corundum is the second hardest gemstone (diamond is the first) and appears red due to a small amount of chromium within the crystalline structure of the stone itself. Sometimes, small needles of a mineral called rutile give rubies a 'silky' appearance. Depending on the arrangement of these rutile needles, light can be reflected in a star-like way off of the stone's surface.
The only difference between rubies and sapphires are the included impurities found in each. They are both the same, exact stone... corundum. In sapphires, however, instead of chromium, titanium and iron impurities will be found. Rutile inclusions can also be found in sapphires and provide the same silky or star-like quality, although this is not as common in sapphires as in rubies.
Emeralds are beryl crystals which also contain a small amount of chromium impurities. The chromium, in this case, absorbs a different part of the light spectrum than the chromium in rubies thanks to the crystalline structure of the beryl. In this case, the stone will appear green instead of red. Aquamarines are another type of beryl with different included impurities.
The host crystal aluminum fluorosilicate becomes known as topaz when small quantities of iron impurities are found in the stone. Different types of impurities in this crystal produce different colors, but the resulting stones are still typically known as topaz. Blue, pink, and orange topazes are almost as popular as yellow topaz.
If you are in the market for a specific colored gemstone, a little research can help you to make your decision. For example, rubies and sapphires are expensive, but red garnets and blue topazes are considerable more affordable. Obviously, your gemstone budget will be the deciding factor in most cases. Thankfully, there are many ways of achieving the same effect when it comes to gemstones.
When you are ready to add to gemstones to your collection, visit U.S. Auction Online to make a bid, or you can register to view winning bids to get an idea of the value of gemstones that you already possess.
Image via: https://en.wikipedia.org/wiki/Gemstone