Solitaire lady engagement ring

Circa 1920 Art Deco / European Origin.
950 platinum

1 Full Cut Central Brilliant 0.55ct. of excellent color E,
IF purity.
6 Brilliant sides of 0.02ct. each of excellent color and purity.
Total: 0.67ct.

Weight: 3.9 grams
Measurement of Ring No. 18
1.8cm inner diameter. Sealed.