This type of enhancement is considered permanent under normal wearing conditions, except the flame of a jewelers torch and/or boiling acids and bases may compromise the integrity of a CE diamond's enhancement.In the event the integrity of the enhancement is compromised, a CE manufacturer can restore the enhancement should this occur.Type I stones are usually eye-clean with no inclusions visible to the unaided eye.

zircon age dating-45

In a stone with a window that occupies over 50 percent of the face-up area, the gemologist also grades the window as the dominant color and then the brilliance as the additional color. If it does not appear to be grayish or brownish at all, it has strong to vivid saturation.

Lastly, the gemologist estimates the saturation level. Saturation is also where any additional colors such as those due to color change, pleochroism, color zoning, and windowing less than 50% are noted.

Tone should be considered along with the Color to properly understand the depth of color in the gem.

Even though it may have good primary color, if it's too light in tone, it will not be rich enough... if the color is too dark, it will sacrifice brilliancy and transparency. in strong, diffused, daylight-equivalent lighting, with the light source somewhere around 10 in. The stone is then rocked back and forth up to a total of 30 degrees as the tone, hue, and saturation judgments are made.

The 3 charts below are based on the GIA (Gemological Institute of America) "Color Stone Grading System", where the Color with it's various Hues, the Tone, and the Saturation of color in a particular gem is listed.

You will normally see this system identified by a letter or set of letters, followed by two numbers.

The letters are abbreviations of the Color and Hues visible...

the first number is the Tone or lightness/darkness of a particular gemstone...

The sample stone is green, with a touch of blue, so the gem is very slightly bluish green.

The hue shows up as bright flashes of brilliance when you look at the stone in the face-up position.

You will find that our "Enhancement Codes and Treatment Terms" explain the majority of treatment methods used in the Gem Trade.