Presidium manufactured the Presidium Screener-II to aid in the separation of synthetic Type IIa colorless diamond from naturally occurring Type Ia colorless diamond. Type IIa colorless diamond is most likely produced by chemical vapor deposition (CVD) or high pressure high temperature (HPHT) synthesis.
Type Ia and Type IIa diamonds each absorb a variable amount of UV light under this severe UV irradiation. Diamonds of type IIa have a low capacity to absorb UV light because they permit deeper UV light to flow through. The distinction between colorless Type Ia and Type IIa diamonds can be distinguished thanks to this difference in light absorption.