Grading System

C

larity refers to the relative degree to which a transparent gemstone is free of internal or surface characteristics or imperfections. Internal characteristics are commonly referred to as inclusions and external characteristics are commonly referred to as blemishes in the gem trade. The types of inclusions encountered in gems include needles (mineral fibers that formed during crystallization), crystals (small mineral crystals of the same or different type as the gem that formed in the host), pinpoints (tiny crystals), feathers (natural separation across an atomic plane), fingerprints (a healed or partially healed break in the gem), color zoning, chips, scratches, etc.,

There for Ceylon Natural Gems was categorize stones in to four different groups such as Eye Clean,Very Slightly Included,Slightly Included and Included.Details are follow.

Eye Clean (EC)

This is the best grade that I will give a stone. It means that with the naked eye the gemstone appears to be clean with no visible inclusions or flaws.It is possible that there might be very minute inclusions which I simply have not seen. In the industry there is one higher grade : Loupe Clean. This is using a special X10 magnifying glass to inspect the stone and finding no inclusions or flaws.

Very Slightly Included (VSI)

I usually apply this grading to a gemstone if it has only one or two very small/minor inclusions. This is usually a single spot, bubble, needle or veil that is almost impossible to see under normal conditions. The overall beauty of the gemstone is not affected at all.

Slightly Included (SI)

This gemstone may have slightly more minor inclusions. None of them detract from the overall beauty of the stone in a noticeable manner. Generally these inclusions would be hard to detect once the stone has been set.

Included (I)

An included gemstone has multiple inclusions of the same or varied type. These are noticeable and must be considered. Setting the stone will not hide the inclusions

Terms Using For Gem Trade

The term artificial is a catch-all for any man made or lab-created gem. Artificial gems that have the same chemical,optical,and physical properties as their natural counterparts are more accurately described as synthetic. Any gemstone not of natural origin is considered artificial in gemological terms.

Clarity has been improved with colorless glass, oil, plastic, resin or some similar substance.

Color has been improved by various processes or agents.

Durability is defined as a combination of hardness, toughness, and stability.

A process that improves a natural gemstone's appearance or durability by an accepted industry practice. Examples:heated citrine, bleached Akoya pearls

Hardness is the ability to resist scratching.

A naturally occurring gemstone that has only undergone the standard process of cutting and polishing.A stone with natural and artificial components, where the two cannot be separated. New category created by a new generation of treatments that add materials to a natural base material. In most cases, undesirable elements of natural material are removed and replaced by added artificial gem material; lead glass, polymers or synthetic material.

See stimulant. The term imitation is used to describe any material that mimics the appearance of a natural more expensive gemstone. Imitations may be man-made or natural. Examples: red glass (imitation ruby), white YAG (imitation diamond), red garnet (imitation ruby)

The term lab created is used to describe any material made by man. Lab-created gems with no natural counterparts fall into the category of artificial, and are used as stimulants. Lab-created gems that duplicate the same chemical, optical,and physical properties as their natural counterparts are more accurately described as synthetic.

A naturally occurring gemstone that has only undergone the standard process of cutting and polishing.

The term stimulant is synonymous with substitute or imitation. A stimulant only mimics the appearance of another more expensive gemstone. A stimulant usually indicates a man-made material, but may be natural. Examples: red glass (ruby stimulant), white YAG (diamond stimulant).

Stability is the ability to remain unchanged in the presence of heat, light, and/or chemicals.

Routine cleaning and bleaching of cultured pearls.

The term synthetic is used to describe a lab-created gemstone that has a natural counterpart. Synthetic gemstone have the same chemical, optical, and physical properties as those occurring in nature. Examples: synthetic sapphire, synthetic alexandrite.

Toughness is the ability to resist breakage (deformation in the presence of external forces).

Gemstones that have undergone changes in color, clarity, and/or durability. Processes described as treatments typically go beyond what is considered standard enhancement. Examples: diffused sapphire, Mystic topaz (CVD), irradiated blue diamond.

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