A gold single stone diamond ring

A gold single stone diamond ring,
an old European cut diamond, with an estimated weight of approximately 1.75ct, rub set in white gold to an openwork frame, to yellow gold foliate shoulders and a plain shank, tested as approximately 14ct gold, Polish assay marks for 583 standard, 1931 to 1963, for Warsaw, 3.26g.
Diamond assessed as approximately:
Colour J/K
Clarity SI1/SI2
Finger size M
Sold for £1,600

Condition report:
Diamond measures approximately 7.30 - 7.40 x 4.93mm.
Diamond slightly loose in setting when tapped, but still secure.
Surface marks/scratches to mount.
Shank slightly thinner at base.