Vintage Blue John / Fluorpar Cabochon set Brooch.

Collet set in an oval 9ct Yellow Gold mount.

Gadrooned ropetwist border .

Blue john ;

Bands of Dark purple, through to lilac veining.

Fluorspar ( Blue John ) is a Semi-presious mineral, a form of fluorite.

It is highly sort after for it's ornamental value.

Originating from the mines in the Blue John caverns in the Peak District.

Before it can be worked all genuine Blue John from this region is heated in an oven.Previously it was then placed in a bowl of pine resin (or epoxy resin nowadays) after this process it is reheated in a vacuum oven.This binds the otherwise friable crystal structure,allowing it to be turned on a lathe or saw cut then polished with putty power

(tin dioxide ) applied with a moist piece of felt.

Therefore all the cracks, fractures or flaws visible in the images are natural striations and very secure, unless otherwise stated.

Hallmarked ;

Sheffield 2007

Maker's mark for ;

A H D.

Anthony Stephen Darwent.

Dimensions ;

Brooch ;

Length 29 mm

Width 22 mm

Depth 5 mm

Length of the pin 31 mm

Blue John cabochon :

25 x 19 mm

Gross weight ;

6.4 grammes.

In very good condition.

No damage , chips , scratches or restoration.

Some minor age related surface marks.

The clasp close's securely , along with the safety catch.

The pin is also gold.

Clean and ready for use or display.

Sold with the period presentation box shown.