A beautiful large aqua blue oval faceted stone set in 9ct yellow gold.
A beautiful more affordable eye-catching vintage piece.
 
Paste is a type of high lead content glass used to imitate any gemstone. 
Glass has been used as a gemstone imitation since ancient history as it is more affordable, transparent, can be coloured in many ways and resembles all kinds of gemstones when polished.
In 1674 an English glassmaker, George Ravenscroft patented a new type of glass that was made with a higher lead oxide content. It had a higher Refractive Index than before. It was a brilliant glass with high dispersion.