This is an iconic Victorian style. Here you have three full of fire Opals in a detailed crown with Diamond accents. The ring is hallmarked 18 K and dated 1902. It is size 6 and weighs 2.6 grams. It can be sized but have your jeweler avoid disturbing the hallmarks.
The Opals are on fire with blues Orange yellows and are 6 mm by 4 mm. There are four well matched Diamonds for 0.20 CT tw. Excellent condition. Recently purchased from England.