Large antique Victorian to Edwardian ice clear paste crystal rhinestone oval ring brooch with open backed stones, set in silver tone

Fabulous Victorian or perhaps Edwardian silver tone brooch with an oval ring of beautifully sparkly clear chaton cut rhinestones set with open backs to let the light penetrate.

I have added a video of this piece as I found it impossible to capture the sparkle in still photos. I wonder if the stones are rock crystal, but am listing as glass rhinestones as this is so difficult to determine without being a gemologist. The silver tone metal settings do not test as sterling silver, and I was surprised by this too as the quality feels like silver. It is possible it is a lower grade silver than sterling, but simply listed here as 'silver tone'.

The brooch has a length of 2.5 inches and a width of 1.75 inches. It fastens with a simple hook clasp and pin and is in very good vintage condition.