These vintage Sevres Crystal pieces are rare and highly collectable.
It has an Alexandrite Neomydium colour - which is a fine lilac purple colour in normal light and this changes to a blue or aquamarine under fluorescent lighting.
It has certainly a very fine piece of French mid-century art glass - and is fully marked with the Crystales de Sevres mark on the base, as photographed.
It is a heavy piece and very chunky - with a lobed rim and inside impressed with a pattern of stars.
It is in good condition with no damages.
It has a diameter of 6 inches - and a height of 3 3/4 inches.
Unpacked it is 2.5 kg - so a bit of a beast, weight-wise.
Sadly, this would prevent me from posting it outside of the UK.
Probably a bowl for the more specialist collector of vintage Sevres Glass.