Lovely ring - real feel of the 1930's about it. Classy, Elegant Sophisticated - woman of the world type ring ( rules me out but I have always wished the inner me could escape).
Dates from the 1930's to 40's . An asymmetric ring set with a spray of Swiss cut and single cut white diamonds, encompassing a dark red cushion cut , slightly oval red ruby. 
The diamonds are clear white shining & brilliant and range around the 2.5mm diameter, 15 in total and roughly 1ct.
The dark red ruby is moderately included - its natural - 6.5mm long, 6mm wide , roughly 1ct . 
The plain well shaped shank is in white gold and marked in a lozenge for 18ct gold. The shape of the lozenge indicates it may be Italian or as the cut indicates, Swiss. 
Size L (UK) 5 1/2 (US) - it has been sized once, not surprising, the 1930's lady was a slighter build than we are , but can take sizing again. It is a very well constructed piece.
Weight  5.35 gms.