Shapes & Cuts:
There are a plethora of different gemstone shapes and cuts. However the most common shapes are:
Round - Oval - Pear - Emerald/rectangle - Trillian/Triangle - Princess/square
Each shape can have a different type of cut; Brilliant cut, Concave cut, Checkerboard cut and the list goes on and on. Each year gem cutters find another way to bring out the color, fire and brilliance of a gemstone.
Clarity - Colored gemstones:
Colored gemstones are usually only graded by Clarity. Clarity includes things such as cracks, chips, and particles or air trapped in the gemstone. Other faults can be the color of the stone, cloudiness and/or evenness of the color. A deep rich clear purple Amethyst is of higher value than a cloudy light purple Amethyst.
Here are the different grades from best to worst:
IF - Inclusion Free (not always used)
VVS - very very slightly included
VS - very slightly included
SI1 - Slightly included
SI2 - a little more included than SI1
I1 - Imperfect
I2 - more imperfect
I3 - very imperfect
VVS and VS have inclusions that can only be seen under magnification.
SI1 and SI2 have inclusions that can be seen with the naked eye.
I1, I2 and I3 have obvious inclusions.
The clarity grading system varies according to the type of the gemstone. There are three different types:
spacespaceType 1 gemstones are normally eye clean and exhibit few if any inclusions. Even minor Inclusions in these gemstones lessen their value
spacespaceType 2 gemstones are prone to inclusions and normally exhibit inclusions. Minor inclusions do not detract from these gemstones.
spacespaceType 3 gemstones are very prone to inclusions easily seen by the naked eye. These inclusions are considered a part of the gems beauty.
spaceType 1 gemstoned include: Aquamarine, Kunzite, Morganite, Tanzanite, Topaz and Zircon
spaceType 2 gemstones include: Alexandrite, Amethyst, Garnet, Iolite, Peridot, Ruby, Sapphire and Spinel.
spaceType 3 gemstones include the Emerald, Bixbite and pink Tourmaline.
Clarity ratings in diamonds is a little different than in colored gemstones, remember a 1 grade is better than a 2 grade, they are:
VVS1 & VVS2 - Very very small inclusions
VS1 & VS2 - Very small inclusions
SI1 & SI2 - Small inclusions
I1, I2 & I3 - Included
A carat is simply the weight of the gemstone, one carat equals 0.2 grams. Each carat is broken down into 100 units called points. In other words a 3 carat, 50 point diamond weighs 0.7 grams.
The color of a diamond is graded something like it's clarity:
D, E & F - Colorless
G, H, I & J - Near colorless
K, L, M & N - Slightly tinted
O, P & Q - Very light yellow
R, S & T - Light yellow
U, V & W - Yellow
X, Y & Z - Light fancy
The best grades are at the top and bottom of the scale.
The cut does not apply to the shape of the gemstone but the quality of the cut.
spaceIs the crown of the gemstone too thick or too thin?
spaceAre the cuts uniform?
spaceAre the angles of the cuts too deep or too shallow?
The best cut brings out the best of the diamonds fire.
+1 & 1 - Excellent
2 & 3 - Good
4 - Average
5 & 6 Industrial
Why is hardness important?
The hardness of the gemstone is very important, for the most part very hard gemstones like the diamond can take a lot of traffic, soft gemstones chip and break very easily.
In 1812 a German mineralogist named Friedrich Mohs devised a scale for grading the hardness of different minerals. He took samples of different minerals and gave them a number according to how hard they were. Here is his scale. This scale is exponential; a gemstone with a hardness of "5" is ten times harder than a gemstone with a hardness of "4".
10 - Diamondnnnn9 - Corundumnnnn8 - Topaznnnn7 - Quartznnnn6 - Feldspar
c5 - Apatitennnnn4 - Fluoritennnnn3 - Calcitennnnn2 - Gypsumnnnnn1 - Talc
spaceI do not recommend gemstones softer that a 6 for rings or bracelets, there is too much of a possibility that it could be bumped and broken. Earring's and pendants can spacebe much softer, however anything under a 4 has a good chance of breaking or chipping.
spaceIf you go to my page "Gemstone Information" you will find information on a multitude of gemstones including their hardness.
Here are the approximate hardness' of a few gemstones:
spac1 to 1.9 - Ice (Yes, Ice is a mineral)
spac2 to 2.9 - Selenite (see http://www.crystalinks.com/mexicocrystals.html )
spac3 to 3.9 - Rhodochrosite, Calcite
spac4 to 4.9 - Fluorite
spac5 to 5.9 - Apatite. Obsidian
spacespace6 to 6.9 - Andesine, Labradorite, Moonstone, Zircon, Tanzanite, Peridot, Jade, Kunzite
spacespace7 to 7.9 - Amethyst, Citrine, Tourmaline, Emerald, Aquamarine, Garnet
spacespace8 to 8.9 - Topaz
spacespace9 to 9.9 - Sapphire, Ruby, Cubic Zirconia, Moissanite
spacespace10 - As hard as it gets - Diamond
The density of a gemstone does not effect the quality, price or rarity of a gemstone. It will, however, give you an idea on the size of the stone if you are only given it's weight. In other words a 3 carat Amethyst is going to be larger than a 3 carat Zircon. Here are the approximate densities of some popular gemstones, you will see that hardness and density do not relate:
Amethyst - 2.65speEmerald - 2.8speTourmaline - 3.0speTanzanite - 3.3spDiamond - 3.5eacGarnet - 3.5 to 4.3speSapphire - 4.0spZircon - 4.7
Mystic gemstones are gems that have been treated with a patented process called "Azotic Coating". This is a process that plates the top of the gemstone with a very thin layer of aluminum. The aluminum causes a brilliant flash of colors on the face of the stone. Because this process is patented, sellers in Asia often call these gemstones "Rainbow" instead of Mystic. This treatment is common in topaz and quartz gemstones.
Because of the high price of natural gemstones many gems sold today are made in a laboratory. To be lab created (aka - synthetic) the gem must be identical to the natural gemstone in every way; hardness, composition, luster, looks etc. A ruby that came out of the ground is the same as a lab created one, the only difference is that nature made one and man made the other.
Corundum (Sapphires & Rubies) is fairly easily created in the lab, therefor lab created Rubies & Sapphires are very common. Beryl is the mineral Emeralds and Aquamarines are made of and is not easily made in the lab. Lab created emeralds are very expensive and not often seen in jewelry (Aquamarines are inexpensive enough that only very large gems are made in the lab).
Lab simulated gems are only made to look like the real gem. Most lab created gems are made of cubic zerconia or glass.. Most low cost emerald jewelry is made with lab stimulants due to the fact that lab created emeralds are very expensive to make.
There are aslo simulated gems not made in a lab. These gems are sometimes called "Crystal" and are basicly colored quartz.
If you have any questions you can email me at: email@example.com