Signature Small Studs (Crystal Quartz)A smaller and more delicate version of the best selling Signature Midi Knockout Studs, the Signature Small Knockout Studs feature multi faceted, brilliant cut gemstones that make an impact for both day and night. Gemstone: Crystal Quartz (Semi Precious). Our semi precious gemstones are rare, ethically sourced and hand cut from naturally occurring materials, giving each individual stone its own unique colour. Note: stone colour per piece may vary.