Colored gemstones have a language all their own. Unlike diamonds, there is no universally agreed-upon gemological grading system to use when discussing the quality of colored stones. But it is important to learn that three different experts in this field will reach similar conclusions about the quality and value of a particular colored stone, even though each may use different language to describe it.
Colored gemstones and jewelry are sold by brick and mortar and internet jewelry stores, pawn shops, auctions and on home shopping networks. But there are only a handful of jewelers/gemologists who are experts in the field of colored stones. As always, know your jeweler and know his/her expertise. Find an expert, and you will buy something special that will be enjoyed by future generations in your family.
Colored gemstones are more complex than diamonds. This is because nature produces so many species and varieties, and each variety grows in so many different shades and intensities of color. As an example, the purple amethyst quartz, the birthstone for February, grows in tones from very light violet to intense rose violet and costs from $2.00/carat to $800/carat. All colored gemstones have broad price ranges like that of amethyst, and these are based on carat weight, quality, history, demand, durability, comparative rarity, fashion and in rare cases geographic origin.
Like diamond, the heavier the colored gemstone the more expensive, all other factors being equal. Like diamond, there are 100 points to a full carat. Some colored stones are not weighed. Rather they are sold based on their physical dimensions. Examples would be the opaque colored gemstones like malachite, sugilite, lapis, coral, shell, chalcedony, cinnabar and of course the two jades, nephrite and jadeite, among many others.
Based on the comparative rarity of colored gemstone rough crystals, there may be large price jumps at certain carat weights for some colored stones. Sometimes the per carat price jumps at 3 carats; sometimes 5 carats; sometimes 10 carats. While demand is a factor here, the rarity of the rough crystal is the primary determinant of increased cost.
A 2 carat diamond does not occupy the same space as a 2 carats sapphire which does not occupy the same space as a 2 carats rhodolite garnet, and on and on. The atoms of each colored gemstone combine in different patterns, and this creates a distinct density or specific gravity for each species. A 2 carat sapphire might measure 7.6mmm diameter white a 2 carats diamond might measure 8.1mm. While most colored gemstones are priced by the carat, the appearance of the stone in a ring for example is based on its size, meaning its surface dimension. The great designers of colored gemstone jewelry look at surface dimension and appearance rather than carat weight.
The quality of a colored gemstone is based on Color, Clarity, Shape, Cut and Laboratory Enhancements to Color and or Clarity. Of these factors, COLOR is the primary ingredient of cost and beauty. (Note the comparison with diamond where it is the cut, meaning the quantity and quality of brilliance and fire that is the primary ingredient of cost and beauty).
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