F

Facet

One side or flat surface or plane of a cut gem. A facet can be any shape, but usually some kind of triangle or kite shape.

Faceting

The art of cutting and polishing the surfaces/planes of a cut gem. A modern brilliant diamond usually has 57 or 58 facets.

Fancy

Naturally coloured diamonds that fall outside the normal colour range are called fancy diamonds. They are either yellow or brown diamonds that have more colour than a Z grade, or are a colour other than yellow or brown. See The Four C’s.

Filigree

Delicate ornamental work created from a thin wire of metal and fashioned into an ornate or fanciful design.

Fluorescence

The natural visible emission of light/glow (usually blue/yellow) when a gemstone is subject to UV light. A 1997 survey by GIA concluded that fluorescence does not negatively impact the face up appearance of a diamond.

Flush

A term used when two materials are sat next to each other at the same level, for example when a wedding band sits right next to an engagement ring it is said to sit ‘flush’. A flush setting is used to describe when the table (top) facet of a gemstone sits in line with the bezel (surrounding metal) setting.

Foil Backed

Used to describe a stone when a piece of foil (often coloured) has been set behind the stone. This was popular in Georgian era, particularly with aquamarine pieces.