Clarity

Inclusions can be the signature of a diamond€™s natural origin. The type and arrangement of inclusions are like the fingerprint for a diamond, being unique from stone to stone. The arrangement of inclusions allows a stone to identified by a €œmap€ of these on the certificate. The first detailed clarity grading system was developed in the 1950€™s. This initiated the standardising of grading around the world.

Determining clarity of a diamond refers to assessing the presence of both internal and external marks. Inclusions are located within the stone and may possibly extend to the surface. Types of inclusions are feathers, mineral crystal, and structural defects. Some inclusions may result from an artificial treatment, such as laser drill holes.

External features or blemishes are scratches, nicks, pits, abraded facet edges, extra facets and naturals.
As diamonds form deep within the earth€™s mantle, the extreme conditions during formation and upon extrusion to the surface, makes it rare that a diamond will survive intact. Diamonds free of inclusions are extremely uncommon and therefore more valuable. Minor inclusions will lower the price of the diamond without affecting its overall beauty. A diamond of high clarity combined with a fine quality of cut allows light return to be maximised. Slight differences in clarity can have a significant on price.

GRADING TECHNIQUE

To accurately grade clarity, a stone must be loose, as jewellery settings can hide inclusions and blemishes. For stones mounted in jewellery, a clarity grade can only be estimated.

Diamonds attract grease and dust to the surface, therefore, it is important to firstly clean the stone thoroughly, to avoid an incorrect verdict. The stone should be held with tweezers, not picked up with fingers, as this will transfer grease to the stone€™s surface. Due to the reflection of facets in a diamond, surface dirt can easily be mistaken for an inclusion or blemish.

The international standard for assessing clarity is a fully corrected triplet loupe of 10 X magnification. If the lens has not been corrected, it will make objects appear distorted. Clarity should only be assessed by viewing the diamond face-up and only under 10 X magnification. Although looking through the pavilion helps to locate the position of an inclusion, clarity is only assessed by what is visible through the crown.

When determining the clarity of a diamond, several steps need to be followed.

Firstly, the size of the inclusion is observed relative to the size of the stone. Inclusions can range in size from minute mineral crystals to large feathers. Larger inclusions are more visible and can obstruct the light paths in the diamond resulting in reduced transparency.

The quantity of inclusions is considered along their location within the stone. Inclusions located under the table are usually more easily seen than if they were positioned near the girdle. The reflections of the facets towards the girdle can reduce their visibility. Inclusions are seen in various colours and the colour may influence how easily it is seen. The nature or type of inclusion is also taken into consideration, particularly if it affects the durability of the stone.