This upgraded Presidium Screener now tests for diamond melee as small as .02 carats by using UV absorption. The unit helps screen out Type IIA colorless diamonds, which are likely to be synthetic and created through CVD or HPHT synthesis. Type IIA diamonds allow deeper UV light to pass through the stone, allowing you to differentiate between colorless Type IA and Type IIA diamonds. The color coded indicator lights give a low or high reading of UV light absorption—Blue indicates a natural diamond and Red indicates a type IIA diamond. This unit will test diamonds up to 10 carats in size in a variety of cuts including brilliant round, emerald, and baguette. This screener can be used on both loose and mounted diamonds. Upgrade your diamond screener today by visiting Stuller.com/tools.