Onyx

In Victorian mourning jewellery, onyx was the stone of the second stage of mourning. While jet dominated deep mourning with its matt, body-warm black, lustre was permitted to return to a mourning piece with onyx only once the first year of mourning had elapsed. Unlike jet, onyx is an inorganic material - a black variety of chalcedony, that is, finely crystalline quartz.

Material properties

Onyx is hard (Mohs 7), cool in the hand and takes a very high polish. The colour is deep black, often with an almost bluish sheen in raking light. Genuine onyx today is almost always dyed chalcedony: the natural material usually shows banding (hence the cognate term sardonyx for the red-brown striped variety), and the uniformly black colour is produced by a traditional dyeing method - steeping in a sugar solution followed by treatment with sulphuric acid. The process has been customary since the 19th century and may be assumed for the great majority of historical pieces.

The most important deposits lie in Brazil (Rio Grande do Sul) and Uruguay; India supplied smaller quantities in the 19th century. In contrast to jet with its Whitby monoculture, onyx production was always broadly based - which made onyx markedly cheaper than jet in the Victorian market.

Onyx in Victorian mourning jewellery

The Victorian court mourning code recognised three stages (see Widow's Jewellery). In the first stage all lustre was prohibited; only matt, organic materials such as jet, vulcanite, Berlin iron and black enamel on gold were permitted. The second stage allowed lustrous black, small accents in white and gold settings as restrained framing - here onyx became the principal material.

Typical pieces of the second stage:

• Mourning ring with an onyx cabochon, often with an inlaid white inscription (In memoriam, date of death)
• Mourning brooch with a central onyx stone, framed by small seed pearls
• Pendant with an onyx plaque and gold engraving on the reverse
• Cufflinks for widowers - onyx was tolerated here even in the first stage, because the material was less conspicuous on men

The gold settings were usually 9 or 14 carat; higher carat values appeared too ostentatious for mourning jewellery.

From mourning stone to Art Deco material

With the end of formal court mourning around 1900, onyx lost its mourning context but paradoxically became more popular: the Art Deco of the 1920s and 1930s loved the geometric combination of onyx black, rock-crystal white and diamond accents. Cartier, Van Cleef & Arpels and Boucheron worked intensively with onyx in this period, though now as a fashion material rather than a mourning stone.

Onyx is thus one of the few historical mourning materials to have survived a clear change of genre - unlike jet or vulcanite, which disappeared from jewellery practice almost entirely with the end of Victorian mourning.

Onyx today

In modern memorial jewellery, onyx appears in three contexts:

1. Classic material in timeless rings - often as a cabochon without any declared mourning reference.
2. Carrier for laser engraving - the polished onyx surface takes laser engraving with high contrast (white line on black ground). Initials, dates and occasionally fingerprint lines are cut directly into the stone.
3. Ground stone for inlay work - an onyx plaque as a carrier surface, into which a gold or platinum inlay carrying the line pattern of a fingerprint is set. The technique is established in high-quality memorial jewellery.

When buying historical pieces, two points deserve attention: whether the material really is onyx (frequently confused with French jet, that is, black glass - glass is colder and lighter), and whether the dyeing is permanent (very old dyed pieces can go matt on contact with perspiration).