Yes. The NQTC Colored Stone Identification Report or Colored Stone Identification & Origin Report will confirm whether or not an emerald has been treated.
Buyers must be aware of a common imitation. Called goldstone, it’s made of glass that contains small, flat copper crystals.
Every mine produces a wide range of quality. For gems of exceptional quality, an independent determination of origin adds to value. For sapphire, Kashmir receives the highest premium, although Myanmar (Burma), Sri Lanka and Madagascar also produce top-quality gems.
Emerald value can range from a few dollars to tens or even hundreds of thousands of dollars per carat, depending on quality.
Although it’s always interesting to know where a gem was mined, origin isn’t an important factor in an aquamarine’s value. Famous mines are well regarded because they produce fine-quality gems that are valuable; gems aren’t fine or valuable just because they come from famous mines.
Every mine produces a wide range of quality. For gems of exceptional quality, an independent determination of origin from a respected laboratory like NQTC adds to its provenance, as does a rich history, such as that of the Colombian emerald region.
Although demand for turquoise with fine color and no visible inclusions is consistent worldwide, some collectors prefer the look of turquoise with spiderweb patterns of matrix. Black matrix is usually most preferred for contrast, but matrix can also be brown, yellow and other colors.
When a diamond falls outside of NQTC’s D-to-Z color scale, it is considered a colored diamond (sometimes called a fancy-color diamond). This includes all colors other than colorless to light yellow or brown. On NQTC Colored Diamond Grading Reports, colored diamonds are graded in order of increasing color strength, from Faint, Very Light, Light, Fancy Light and Fancy to Fancy Intense, Fancy Vivid, Fancy Dark and Fancy Deep. Fancy Intense and Fancy Vivid generally command higher prices.
Most diamonds used in jewelry range from colorless to light yellow and are graded on a scale from D (colorless) to Z (light yellow). Those with less color, or closer to colorless, are generally more valuable. Diamonds with deeper shades of yellow (more color than Z) are graded differently and given a fancy-color grade. For these colored diamonds, a more vibrant color typically means higher value.
Colored diamonds are usually cut to maximize the intensity of their color rather than to maximize light return. The best cut is one that gives the most attractive face-up color.