Color
Hopefully you have familiarized yourself with the characteristics used to estimate the value of a diamond – color, clarity, carat and cut. These same characteristics are used when judging colored stones but because of the nature of different stones these characteristics affect the overall value differently. Where as clarity most affects the beauty of a diamond, the beauty (and therefore value) of colored stones are most affected by color.
Color is by far the most important characteristic when considering gemstones other than white diamonds. Whatever the color of the gem you are considering the most valuable will be as vivid and saturated as possible. Everything else being equal a gem without dark areas where the color is hard to make out will be more valuable the one than one that is over dark. Color zoning (this look like layers of color and clear) should also be avoided.
Cut
There are no "ideal cut" colored gemstones but choosing a well cut stone is relatively simple. As you examine a stone face-up you should see the main color evenly throughout the entire stone. Avoid stones that appear to have washed out areas or windows. Equally important is the angle of the facets in relation to each other. You don't need a college degree to understand the effect of this; just gently rock the stone to see the light reflect off of the facets. Look at both the top facets and through the stone to the bottom facets. A well cut stone will sparkle and look full of life. You want a stone that looks good in movement as you will want to wear it in jewelry that moves; a necklace, earrings, a bracelet, a ring. Stones can be re-cut but this can be expensive. Before looking into this option realize that you must not only pay the lapidary (stone-cutter) but you will also lose carat weight thereby greatly increasing the price per carat of your stone.
Clarity
In Diamonds, inclusions are relatively rare, and so when they are present they can affect the value. Color gemstones on the other hand are more likely to have inclusions so do not affect value as greatly as they would in diamonds. Sometimes inclusions will identify a gem as natural, treated, or synthetic. Sometimes inclusions can reveal a gem's origin. Sometimes inclusions will actually increase the value of a gem like those inclusions found in phenomenal gems like Cat's Eyes or Stars
Carat
Carat is a unit of weight with 5 carats equaling 1 gram. Because different gemstones are made up of different elements they will weight differently. More simply put; 1 Lb of feathers will take up more space than 1 lb of gold. Similarly a watch made from titanium will weigh less than the exact same watch made from stainless steel. Many people know about what size a well cut 1 ct diamond will be but many do not realize that a 1 ct diamond-cut (cut with the proportions of a diamond) sapphire will be smaller because sapphire is heavier than diamond. Conversely a 1 ct Amethyst will be slightly larger because its lighter.
Hopefully you have familiarized yourself with the characteristics used to estimate the value of a diamond – color, clarity, carat and cut. These same characteristics are used when judging colored stones but because of the nature of different stones these characteristics affect the overall value differently. Where as clarity most affects the beauty of a diamond, the beauty (and therefore value) of colored stones are most affected by color.
Color is by far the most important characteristic when considering gemstones other than white diamonds. Whatever the color of the gem you are considering the most valuable will be as vivid and saturated as possible. Everything else being equal a gem without dark areas where the color is hard to make out will be more valuable the one than one that is over dark. Color zoning (this look like layers of color and clear) should also be avoided.
Cut
There are no "ideal cut" colored gemstones but choosing a well cut stone is relatively simple. As you examine a stone face-up you should see the main color evenly throughout the entire stone. Avoid stones that appear to have washed out areas or windows. Equally important is the angle of the facets in relation to each other. You don't need a college degree to understand the effect of this; just gently rock the stone to see the light reflect off of the facets. Look at both the top facets and through the stone to the bottom facets. A well cut stone will sparkle and look full of life. You want a stone that looks good in movement as you will want to wear it in jewelry that moves; a necklace, earrings, a bracelet, a ring. Stones can be re-cut but this can be expensive. Before looking into this option realize that you must not only pay the lapidary (stone-cutter) but you will also lose carat weight thereby greatly increasing the price per carat of your stone.
Clarity
In Diamonds, inclusions are relatively rare, and so when they are present they can affect the value. Color gemstones on the other hand are more likely to have inclusions so do not affect value as greatly as they would in diamonds. Sometimes inclusions will identify a gem as natural, treated, or synthetic. Sometimes inclusions can reveal a gem's origin. Sometimes inclusions will actually increase the value of a gem like those inclusions found in phenomenal gems like Cat's Eyes or Stars
Carat
Carat is a unit of weight with 5 carats equaling 1 gram. Because different gemstones are made up of different elements they will weight differently. More simply put; 1 Lb of feathers will take up more space than 1 lb of gold. Similarly a watch made from titanium will weigh less than the exact same watch made from stainless steel. Many people know about what size a well cut 1 ct diamond will be but many do not realize that a 1 ct diamond-cut (cut with the proportions of a diamond) sapphire will be smaller because sapphire is heavier than diamond. Conversely a 1 ct Amethyst will be slightly larger because its lighter.