Gemstones

Color
For colored gemstones, the richer and deeper the color will be assigned a higher grading. When enquiring about gemstones you will hear the common terms like “cornflower blue” for sapphires and “pigeon-blood red” for rubies. These terms are helpful but lack the accuracy of stone grader.
For a more precise and accurate description of gemstone color, it’s helpful to divide color descriptions into three components: hue, saturation, and brightness. These three components are often used together to describe an individual gemstone’s color.
Hue refers to the basic colors of blue, green, yellow, orange, red, purple, and violet, as well as transition/modified colors like bluish green and yellowish green
Saturation means the gem has good strength, purity, intensity, and depth of color. Colors of low saturation are sometimes called weak, grayish, or brownish, while those of high saturation are said to be highly saturated, strong, or vivid.
Brightness is the degree of color brightness and darkness. Gemologists sometimes use terms such as light, medium light, dark to describe a stone’s brightness.

Clarity
Clarity refers to the presence (or absence) of impurities, blemishes or other identifying characteristics either internally or externally on the gemstone. Gemstones are created deep within the earth, so most gems contain unique birthmarks called inclusions (internal) and blemishes (external).
Clear transparent gemstones with no visible flaws are the most valued, but completely flawless gemstones are very rare. Some gemstone varieties, notably emerald and ruby, typically have some eye-visible flaws so the price structure takes this into account. On the other hand, gemstones such as aquamarine, citrine, and topaz are normally eye-clean, and as a result there is a less tolerance for noticeable flaws for these gemstone varieties.

Size
Like diamonds, colored gemstone weight is measured in carats. However carat weight is not always the best way to judge the size of a gemstone. For this reason we also show the length and width or diameter in millimeters.
Like diamonds size affects price greatly and in a non-linear way. For example a 2.00 carat ruby would have a much higher price than a 1.99 carat ruby.

Cut
Cut quality refers to the proportions and finish of the gemstone. This is a crucial factor because it affects the brilliance and color of gems, but its importance is not always reflected in the price of colored gemstones. Cutters always strive to achieve the best color possible from the gem. Even color distribution all across the stone is an important factor with gemstones and this is affected greatly by the depth of the stone. On the other hand a very deep stone has high carat weight relative to its face-up size.
Therefore the best cut stone has excellent even color without being a very deep stone.

Treatment
Most gemstones are treated to enhance their appearance. Most treatments are permanent have been used for 100’s of years.
Heat treatment is most common method of treatment. To date, this technique is still routinely used on most gemstones. Its aim is to re-create the condition that would have been present during its creation and allow the work began by nature to be completed. The result is a gemstone with more even color distribution and reduced visible flaws. Heat treatment is permanent.
Heat treated sapphires and rubies make up more than 90% of all gems and untreated stone with excellent color command a large premium in the market.