Looking for something a little different to your regular round stone, you need this square Simulated Diamond stone is 2.5mm, so noticeable sparkle. It comes in Silver, Yellow Gold or Rose Gold. 
 
Specifications
Length: 6 mm
Stone Type: Simulated Diamond
Stone Colour: Clear
Stone Size: 2.5 mm
Finishes Available: Polished Silver, 14ct Yellow Gold Ion Plated, or 14K Rose Gold Ion Plated
Base Metal: 316L Surgical Steel