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Diamonds Cut

Diamonds

Too shallow

A diamond with too shallow cut does not reflect light in the spectrum which it should achieve. This means that the diamond loses some of its luster.

Ideal

A diamond with ideal cut reflects light with minimal loss which maximizes the diamond’s luster.

Too deep

A diamond with too deep cut reflects light to the sides which means that the diamond looks very dark and dim.

A diamond’s luster is determined by the cut. There is no simple scale which can describe the diamond’s luster, it is graded according to many different factors. The relation and proportion between the diamond’s reflections, symmetry and quality of cut must be studied.

Many gemologists consider the cut the most vital element in evaluating a diamond. The reason is that a diamond with high colorlessness and good clarity looks much worse with a bad cut. A good cut emphasizes the diamond’s refractive index and dispersion (dispersion is the stone’s ability to split reflected light into many colors) better than in a badly cut stone.

When you grade a diamond’s cut, you should, however, take into consideration more factors than just depth and width. Today the luster of a diamond is measured by computers and sophisticated software.

Brilliant cut

The most common form of cut is called a brilliant cut. The cut has 57 facets, 33 facets on the upper part(crown) and 24 facets on the lower part (pavilion). It can happen that the top (culet) is cut as well and then the brilliant has 58 facets. The ideal proportions of a diamond have changed with time but whatever the proportions, the brilliant cut is considered the best to elicit the diamond’s special optical features like brilliance and the best possible way to split the light. There are many versions of brilliant cut, e.g. navette, drop and oval cut.

Anatomy of a diamond

A) Diameter: Diamond diameter is measured from side to side at the girdle.

B) Table: The table is the biggest facet of the diamond.

C) Crown: The upper part of the diamond is called the crown. It spreads from the girdle up to the table.

D) Girdle: The girdle is a small edge dividing the crown from the table. It should be evenly curved. It should be obvious that the stone should be round but the cutter sometimes wants to get as much as possible from the raw material.

E) Pavilion: The pavilion is the lower part of the diamond. It spreads from the girdle to the culet.

F) Culet: The culet is the little facet at the base of the brilliant. With a good cut the culet is not visible to the naked eye.

G) Depth: The diamond’s depth is measured from the culet to the table.

Polishing and symmetry

The polishing of a diamond is a synonym of its evenness. If the diamond is not accurately polished it can look very dark and dim. If the relation between the facets is not symmetrical the reflected light can go in the wrong direction which means that the diamond loses its luster. Symmetry and polishing are described in the certificates which come with all diamonds from Lamastone and are issued by a third party. The quality of a diamond’s cut is divided into five categories:

Ideal: Reflects almost all light which enters the diamond. About 3% of all diamonds are of this quality.
Very Good: Extraordinary brilliance. About 15% of all diamonds are of this quality.
Good: Good brilliance. About 25% of all diamonds are of this quality.
Fair: Lower brilliance. About 35% of all diamonds are of this quality.
Bad: Brilliance is significantly lower. Not usually recommended.

Which cut should I choose?

A diamond with very good or good brilliance, and polishing and symmetry which are also good or very good, often means a valuable diamond. You can even choose to sacrifice color and clarity and still have an extremely fine diamond.

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