Professional Jeweler Archive: Trilliant-Cut Gems: Elements of Quality Cutting

October 2004

For Your Staff/Selling Color

Trilliant-Cut Gems: Elements of Quality Cutting

This is the fourth installment in a series explaining quality factors in a variety of shapes to help boost gemstone selling skills

Trilliant-cut gemstones are based on a triangular shape and contain 43 facets. Because of their equilateral form, trilliants return lots of light and color. They’re considered nearly as brilliant as round cuts, so are an optimum choice for customers who like brilliance but want something other than round. Variations include rounded-corner triangles, modified shield cuts and triangular step cuts.

Trilliants work well with light-colored gems – such as diamonds, aquamarines, beryls and white sapphires – where cutters try to maximize brilliance. Some twinned diamond rough is naturally triangular (this kind of rough is called a macle) and so are ideal for trilliants. Macles are flat and often cut into shallow triangular diamonds. Some cutters use trilliants effectively to lighten and brighten the appearance of darker stones such as tanzanites, spessartite garnets, rhodolite garnets and amethysts.

Trilliants aren’t used much for very soft gems, such as apatite, unless the corners are rounded. The tips and culets of trilliants are pointed and thin, making them vulnerable to breakage. Some jewelers bezel-set trilliants, though prongs that protect tips work well and show more of the gem.

Quality Factors for Trilliant Cuts

As you look down on the table and crown facets, you should see the table directly in the center of the gem. Deviations mean other facets don’t align properly, and the gem looks lopsided.

As you look down through the gem, the culet should appear centered in the middle of the table. This shows the pavilion (lower part) of the gem was cut with attention to symmetry.

Inclusions should be concealed toward the points unless their size and type endangers the gem. (A surface-breaking feather could cleave a gem when a jeweler tries to mount it in jewelry).

When you examine the gem in profile, the girdle and table facet should be parallel. The pavilion’s main facet should extend from the culet perpendicularly until it intersects the girdle.

Examine all points of the gem, including the culet, to be sure these vulnerable areas didn’t fracture or abrade during the cutting process or through rough handling.

There should be a few polishing marks as possible, and the surface should appear glossy and reflective. Good polishing helps maximize brilliance and scintillation.

– by Robert Weldon, G.G.

The Importance of Cut

Not so long ago, cutters were instructed to focus on weight retention more than optimum cutting so sellers could garner a higher price for the gem. More recently, a premium has been placed on quality cutting that maximizes beauty. Photo by Robert Weldon.

The top facets.
The girdle around the culet.
The bottom facets.

Illustration by Orasa Weldon.

Copyright © 2004 by Bond Communications