Colored Stones Clarity - AS-Level PDF

Colored Stones 10 KEY CONCEPTS Clarity characteristics that affect transparency, brilliance, or durability have the most influence on value. Cutters often leave cavities in less noticeable areas to avoid weight loss from expensive rough. Five factors determine the influence of clarity characteristics...

Colored Stones 10 KEY CONCEPTS Clarity characteristics that affect transparency, brilliance, or durability have the most influence on value. Cutters often leave cavities in less noticeable areas to avoid weight loss from expensive rough. Five factors determine the influence of clarity characteristics on marketability: nature, size, number, position, and relief. Eye-clean is the highest colored stone clarity grade. An important skill for the successful stone buyer is the ability to quickly judge a gem’s quality with the unaided eye. You should take the time to examine expensive stones carefully with a loupe. Some types of colored stones are typically more included than others, so they’re assessed according to different clarity standards. Key Terms Abrasions—Tiny nicks and pits caused by wear and damage to a gem’s facet edges or culet. Included crystal—A mineral crystal trapped within a gem as it grows. Blemish—Characteristic or irregularity confined to the surface of a polished gemstone. Needle—A long, thin inclusion that can be a solid crystal or a hollow tube that might be filled with liquid or gas. Cavity—An opening that extends into a gem from the surface. Negative crystal—An angular, hollow space within a gem that resembles a mineral inclusion. Chip—A damaged area on a gem, usually near the girdle. Pinpoint—Minute inclusion enclosed within a gem; can occur singly or in groups called clouds. Cloud—Any hazy or milky area that cannot be described as a feather, fingerprint, or group of included crystals or needles. Polish lines—Tiny, parallel grooves on a facet surface left by the polishing operation. Eye-clean—Description for a gem with no inclusions visible to the unaided eye. Relief—Contrast between an inclusion and its host gem. Feather—A general term for a break in a stone. Scratch—A linear scrape, normally seen as a fine curved or straight white line. Fingerprint—Inclusions that form a pattern that often resembles a human fingerprint. 182 Silk—Group of fine needle-like inclusions.