London blue topaz

Inky teal that keeps its depth under lamp light.

On the strand, London blue reads darker than a photograph suggests. Deep steel blue with a green undertone. Closer to inky teal than to sky. Hold one up to a window and the color glows through. Set it on a bench and it goes almost navy in the hollows between the facets. Most are clean enough that nothing interrupts the color, so what you see is depth and the sharp meeting of facet edges. People reach for it when they want saturated blue that still reads as a gemstone.

Where it comes from

Topaz is aluminum fluorosilicate, Al2SiO4(F,OH)2. Hardness 8, with one direction of perfect cleavage. The name comes from a Sanskrit word for fire, and versions of it have been attached to yellowish gems for at least two thousand years. Before the twentieth century, any transparent yellow, brown or orange stone might be sold as topaz, and many early gem traders had no way to tell one material from another. Modern gemology drew the line and made topaz a distinct species. In low to moderate price jewelry, topaz stayed largely yellow to brown until about 1970. Blue is the rare case in nature. One crystal on record came out of Zimbabwe, measuring 4.6 by 4.2 by 3.1 centimeters. London blue names a color rather than a place: a deep tone, darker than Swiss blue. Our strands are cut in Jaipur, India, then chosen one at a time in Cupertino, California.

What tradition says

Wealth is the association topaz has carried longest. Older writing on the stone reaches further, into health and love and astrology, and lists of gem meanings still repeat those pairings. Blue topaz has its own reputation in crystal tradition. It is said to be the calm one of the family, and people have long believed that keeping one close settles the mind. All of that is tradition. Topaz is the birthstone for November. Blue topaz is listed for December as well, in company with blue zircon, tanzanite and turquoise, and older custom names it the gem of the fourth wedding anniversary.

These are beliefs people have held about the stone, told as tradition. They are not claims, and not advice.

How makers use it

We carry faceted pears and marquise, and they go into earrings most often, hung so the beads swing and catch light from behind. Carved melons work as focals, wide enough to hold the color at the center of a piece. At 3mm and 4mm, the beads carry a line of blue without weight. Figure roughly 20 carats per 8 inches at 3mm and 35 at 4mm. Pair them with plain gold or with a warm stone. The strongest strands stay inky under lamp light instead of thinning toward aqua. Topaz runs about a third heavier than quartz, so a matched strand feels dense in the hand.

Looking after it

At 8 on the Mohs scale, topaz shrugs off scratches. Cleavage is the weak point. There is one direction of it, and it is perfect, so a sharp knock against a bench edge can split a bead. Keep the strand out of ultrasonic cleaners. Warm water and mild soap, a soft cloth after. Sunlight does not touch the color.

Sources: Blue Topaz - London Blue and Swiss Blue, What is Topaz Gemstone | Topaz Stone – GIA, December Birthstones: Blue Topaz, Blue Zircon, Tanzanite and Turquoise - International Gem Society, Topaz | Uses and Properties of the Mineral and Gem