Saint Petersburg, Leningradskaya Oblast, Russia A cross section through a man-made quartz crystal, with the center showing citrine and on the exterior rim, dark good colored amethyst. A clear rod of the quartz seed crystals can be seen along with some tiny metal wires that were used to suspend the seed in the growth media in the autoclave, RHC7801, measuring 3 1/2 x 2 1/4 x 1/4 in; together with a single man-made crystal of ametrine from the same source, RHC40206, measuring 2 1/2 x 1 x 1/8 in; and synthetic citrine crystal also from the same source, RHC40204, measuring 2 x 1 1/4 x 1in. (3)