Patent ID: 8289621

Claim:
A dark field illumination apparatus comprising: a base plate; a support tube positioned on the base plate and having an end configured to support a gem; a diffuser structure configured to substantially encircle the gem supported by the support tube; a reflector unit having a reflecting surface positionable over the diffuser structure and to be opposite the surface of the base plate so that the gem supported by the support tube is substantially surrounded by the reflecting surface, the diffuser structure and the base plate, wherein the reflector unit includes an aperture formed in the reflecting surface to allow the gem supported by the support tube to be viewed; and a light unit positioned to illuminate the gem supported by the support tube and so that the gem supported by the support tube is located between the light unit and the reflecting surface; wherein the base plate comprises a material through which light can pass, and the light unit is positioned so that the base plate is located between the light unit and the gem supported by the support tube.