High-carat gold c17th box bezel table-cut diamond element with modern reeded shank. 
The simplicity of this early setting is characteristic of the period where the gold literally appears to almost absorb the diamond.  
Although this style was copied in c19th Renaissance Revival jewellery this element was originally part of a larger c17th  jewel.
The bezel measures 5mm by 4mm and 3mm high.
Size 7.