Citrine
The yellow-to-orange variety of quartz — November's warm birthstone, most of it heat-made from amethyst.
Also known as: Yellow quartz
beginner Often heat-treated amethyst
What it is
Citrine is the yellow, gold or orange-brown variety of quartz (silicon dioxide), coloured by traces of iron. Like all quartz it is 7 on the Mohs scale and durable for daily wear. Natural citrine is comparatively rare; most commercial citrine is produced by heat-treating amethyst or smoky quartz, which shifts the iron colour centres to warm yellows and oranges — a stable, widely accepted treatment.
The reddish-orange "Madeira" tones are especially prized. Brazil is the dominant source, with material also from Bolivia, Uruguay and Zambia. Citrine and topaz share November as a birthstone, and citrine's affordability in large sizes makes it a popular choice for bold statement pieces.