Citrine is the yellow variety of the mineral quartz. The name citrine is derived from the citron - a fruit similar to the lemon. Citrine, in its wide range of shades from sunny yellow to rich gold to burnt orange (referred to as Madeira in the gem trade), owes its color to heat treatment.
Naturally occurring citrine is quite uncommon, therefore smoky quartz and amethyst are heated to produce yellow-orange, hues. The treatment is permanent. Citrine is the alternative birthstone for November and is designated for the 13ch wedding anniversary.