Citrine

Between about 585 and 560 million years ago, the pieces of Gondwana were colliding, and in what is now eastern Brazil granites formed in the crust, the shallower ones with pegmatites rich in gems. In the sea at around the same time, the first large, complex living things were appearing.

Quartz grows in places like these, in veins, in cavities and in the open pockets of pegmatites. In one such pocket, hot water carrying silica filled the space, and silicon and oxygen began to come out of it and lock together on the wall. A crystal of quartz had started, and it grew layer by layer into a prism with pointed faces.

As it grew, it took in traces of other elements, and its structure kept small defects. These gave it its yellow. In some citrine the trace elements matter most, in some the defects, in some colour centres. The yellow belongs to the body of the crystal, all the way through.

In 1965 A. C. McLaren and P. P. Phakey put thin slices of citrine and amethyst under a transmission electron microscope. The beam itself damaged the crystals in tiny spots, and electron spin resonance showed that the spots were tied to iron. The damage showed where the iron was spread through each crystal.

The colour could still change after the crystal stopped growing. Heat and radiation can both alter colour centres in quartz, and some amethyst turns yellow when it is heated. Part of the citrine sold today began that way, heated after mining. Other citrine grew its yellow in the ground.

Yellow quartz was cut long before anyone could explain its colour. In 1978 and 1979, archaeologists cleared a drain beneath the cold-water hall of the Roman fortress baths at Caerleon, in Wales, and found 88 engraved gems that had once been set in finger rings. One of them, about 12 millimetres long, is citrine quartz cut with a crescent moon and seven stars.

To make a bead, a cutter grinds a piece of the crystal into a sphere and polishes it. The prism and its points are gone, and the yellow stays, because it runs through the whole stone. Quartz is about 7 on the Mohs scale.

On the wrist citrine looks yellow to soft orange, and light passes through it. The centre of each bead looks deeper than the rim, where light crosses less of the stone.

The citrine in our strands comes from Brazil and has not been treated, so its yellow is the one it had in the ground. Each strand comes with a Stone Origin Record.

One way to read this: gemmologists describe the yellow of citrine as body colour. It belongs to the quartz throughout, and it shows fully only where light passes through the stone. The colour is in the stone all the time. Light only shows it.

Eyes open, still in love. The meaning is yours.