Glossary
Every technical term the guides use, defined in one place — so the essays can stay essays and never stop to explain themselves.
The guides on this site are written to be read, not to be glossed. Where a term needs a definition, it is here, in full. If you are new to the cut, start with the guide to what a briolette is, then come back.
The Parts of the Stone
| Term | Definition |
|---|---|
| Table | The large flat facet on the top of most cut gems, through which light enters and returns. A briolette has none — this single absence defines the cut. |
| Girdle | The thin band, or edge, at the widest point of a conventionally cut stone, where the crown meets the pavilion. A briolette has no girdle line; its widest point is simply where two rows of facets meet. |
| Crown | The upper portion of a cut stone, above the girdle. The concept does not apply to a briolette, which has no table to crown. |
| Pavilion | The lower portion of a cut stone, below the girdle, which reflects light back up through the crown. A briolette's lower half is faceted like the rest of it. |
| Culet | The small facet or point at the very bottom of a conventionally cut stone. A briolette usually terminates in a point or a small drilled opening instead. |
| Apex | The narrow top end of a briolette, where the stone comes to its point of suspension and where the drilled channel is cut. The apex is the most stress-bearing part of the stone, which is why so much care goes into it. |
| Drill hole | The channel bored through a briolette's apex so the stone can be threaded and hung. Its direction — horizontal for a wire, vertical for a post — determines how the stone can be mounted at all. |
The Cut and Its Optics
| Term | Definition |
|---|---|
| Briolette | A drop-shaped stone covered entirely in triangular or kite-shaped facets, with no table and no girdle, drilled through its narrow end so it can hang and rotate freely. The GIA baseline is 84 or more facets. |
| Double rose cut | A historic faceting style — a domed crown of triangular facets over a flat or faceted base — of which the briolette is often described as an exaggerated, three-dimensional form. |
| Lantern effect | The soft, multi-directional glow a briolette gives off, because it has no table to throw a single bright return of light. It reads as a small lantern rather than a sparkle. |
| Brilliance | The white light returned to the eye through the top of a stone. A briolette trades some brilliance for diffusion and movement. |
| Dispersion | The splitting of white light into spectral colors — "fire". Facet angles and stone type decide how much a cut shows. |
| Dichroism | A property of some colored stones — tourmaline, for example — in which the color changes depending on the direction you look through the crystal. It makes three- dimensional cutting a study in orientation. |
| Pleochroism | The broader version of the above: a stone showing different colors along different crystal axes. A lapidary cutting a briolette in sapphire must orient the rough so the best color settles at the tip. |
Cutting and Mounting
| Term | Definition |
|---|---|
| Lapidary | A person who cuts, shapes and polishes gemstones. A lapidary cuts a briolette by feel, since there is no flat table to index the first row of facets against. |
| Faceting | The cutting and polishing of flat planes, or facets, on a stone. The word describes both the process and the result. |
| Indexing | The setting of precise angles and positions when cutting facets. Conventional cuts index against a flat table; a briolette has none, which is why the work is slower. |
| Wire wrap | A mounting in which fine gold or platinum wire is threaded through the drill hole and twisted by hand, holding the stone without a metal cap. The gentler option for a briolette. |
| Acoustic cavitation | The formation and violent collapse of microscopic bubbles in a liquid, driven by high-frequency sound. It is how an ultrasonic cleaner works — and why one should never be used on a drilled, faceted drop. |
| Type IIa | A diamond classification for stones with no measurable nitrogen and no plastic deformation — chemically the purest type. Most famous briolettes, including the Briolette of India, are Type IIa. |
| Brio | The trade's shorthand for a briolette. You will see it in auction catalogues and stock lists, rarely anywhere else. |
How to Use This Page
Terms above link back into the guides where they are discussed at length. If a word is missing, or a definition is wrong, that is exactly the kind of correction we want — write to the editorial desk. For the shape itself, drawn and labeled, see the anatomy of the cut.