Tantalizing orange coloured sponge coral cabochon designed as a ladies pendant in a hand-made sterling silver setting.
Correctly known as melithaea ochracea, sponge coral is classified as a coral not a sponge but may be freely traded because it's not considered to be endangered. It comes primarily from the South China Sea and is both porous and very soft and grades just 3½ to 4 on Mohs scale of mineral hardness.
Most sponge coral which is used for gemstones has been stabilized because its natural tree-like structure is full of tiny holes which have been created by polyps. When rocks and minerals are stabilized they're filled with a resin or other substance to stop them from eroding or crumbling but this can also be a way of strengthening or repairing the stone so that it may be used for another purpose. The holes give the coral a similar appearance to a sponge hence some claim this is how the name came about.
Sponge coral gemstones are surprisingly light weight but with them also being soft it's important they be handled with care. Whilst not being worn we recommend this gemstone pendant be covered with a piece of material or kept in the pouch that it comes with in order to protect the cabochon from unwanted marks and scratches. Keeping the pendant covered will also help to minimise any build-up of tarnish on the sterling silver.
To see more of the detail in this sponge coral gemstone head over to our page on Flickr and zoom in on the original sized photograph.
Weight (grams) : 23.1 Size (cms) : 5.2 x 3.2 x 0.7