Beautiful and substantial late Victorian pendant / brooch with a mix of diamonds, from old cut and cushion cut and rose cut diamonds set in silver, I think 65 in total.  
The top is designed as a bow, the center an oval domed glass set in gold with blue enamel border.  
The glass is 22 x18mm and in total 50mm x 33mm.  
Some what magnifying.  
Weighs - 14.9g
Excellent condition