A cabochon of Fossil Algae from Cirencester, Gloucestershire, England.

Also known as Beetroot Stone for its unusual purple-pink colouration, the stone is the agatised fossil remains of Solenopora Jurassica, a unique variety of boron-bearing alga which has been dated to 165 million years ago.
The colour in the gem is due to the presence of borolithochrome pigments, boron-rich organic matter which was seasonally deposited in layers of the rock.
This can be seen as the broad coloured bands in the white limestone matrix of this cabochon.

weight:  46.29 carats
shape:   Keystone shape cabochon
dimensions:   37.82 x 30.46 x 4.49 mm
treatment:  None