The 1973 Vintage White Opal Trilogy and Diamond Gold Ring

This ring's three oval opals and four eight-cut diamonds are held in an ornate gallery and shoulder setting. The shoulders are a combined patterning of a claw and heart, and this claw motif is continued on both sides of the ring head. There are slight scratches to the central opal, visible under high magnification, as in our photography.

Hallmarked in 1973 by the Assay Office of Birmingham on their bicentenary for 18ct gold.

Size P UK/AU, 7½ US/CA, 56½ FR/RU, 17¾ DE

Some science notes on opals:

How do opals opal?

Diffraction! You may have heard of refraction, the process behind a rainbow - different colours of light bend to different angles when they pass through a drop of rain, splitting the light into its full rainbow of colours. This is the same sort of thing you may have seen happen with a prism. Diffraction is similar and different. Rather than just redirecting the light, it ends up being split. Opals are the only natural stones known to do this.

What splits the light in opals? During their formation, silicates are deposited in small spheres, and can pack neatly into a grid. As light tries to go through the gaps in these spheres, the silica spheres act as a diffraction grating, interfering with certain colours and allowing others to pass.

What colours will you get? Well, this depends on the size of the silicate spheres inside your opal. The bigger they are, the more towards the red range of the rainbow it will manage to shine back at you. These are the rarest colours found in opals, with smaller silicates sending back colours from the blue end of the rainbow, which is more common. 

(science above helpfully checked by Astrophysicist Dr Jillian Scudder, who can be found on twitter or Instagram @jillianscudder )