Everything you need to know about Citrine, the other birthstone for November

Citrine is a  popular and affordable member of the Quartz group (which includes Amethyst). The name is a derivation of the French word, for the lemon yellow colour that natural Citrines exhibit. Today though most commercial Citrines are actually heat treated Amethysts and are more of a golden than lemon yellow colour. Depending on the source deposit the heat treatment can produce  colours from yellow to gold to orange brown and red shades of transparent quartz. The final result being dependent on the level of heat applied. In ancient times, Citrine was carried as a talisman against the venom of snakes and scorpions. Today they are known in some cultures as the merchant's stone and are associated with success and prosperity.

Citrine 10x10 Square, 4.83 carats

The causal element  that imbibes natural quartz with its lemon yellow colour is a trace amount of Iron (approximately 40ppm). Natural (untreated) citrines are mostly a  pale lemon yellow to golden yellow colour, but recent demand has meant that almost all of the commercially available stones are now heat treated Amethyst, which exhibit a reddish tint to the overall yellow to golden hue of the stones.
Purchasing Citrine

Colour
While natural Citrine is much preferred over the Citrine produced by heat-treating amethyst, it is often hard to source such material as much of the rough currently available, is pre treated at source before it enters the cutting process. Paler more lemon yellow colours are preferable over the darker red tinted treated stones. Although personal preference is always the most important guide.

Citrine 10x5 Marquise, 0.90 carats

Clarity
Citrine, like Amethyst is an abundant member of the quartz group, and as such only  transparent examples  with excellent clarity, should be considered for facetted stones. A lower transparency can be considered for en cabochon cut stones

Cut
Citrines come in a wide range of calibrated shapes and sizes, constrained to a certain extent by the level of colour banding or zoning present in the stone. Portuguese cuts have become popular in recent years due to the additional brilliance added by the extra facets, which allow for more highly zoned stones to appear as consistent colours.
Mineable Deposits

The most important deposits of natural citrine currently in production occur in Brazil and Madagascar. Other locations include Argentina, Myanmar (Burma), Namibia, Russia, Scotland, Spain and the United States.

Citrine - Common Treatments
Natural Citrine is untreated and will typically exhibit some colour zoning, which can be partially dissipated with moderate heating. Most commercially available Citrine in the market have been produced by heat-treating Amethyst. Brazilian Amethyst will turns a light yellow colour at 878oF/470oC, and then a dark yellow to red brown at 1022-1040oF/550-560oC.
Important & Famous Citrine

While the piece in question has long been lost in the sands of time, around 1300 B.C the bejeweled breastplate of Aaron, contained a Citrine representing one of the 12 tribes (Naphtali) of Israel  - Exodus 28:15-30


Citrine is the birthstone for November, sharing this position with Topaz