PRESIDIUM Synthetic Diamond Screener Manual De Instrucciones página 19

If your mounted open-back diamond is in a ring, place the ring in the
centre of the cross-hair marking Ring Guide that is embossed on the
UV light source. The table of the mounted diamond should be directly
facing down on the testing area.
With the ring hung within the Ring Guide area, use the lever to lower
the UV light source. (Fig 2.6)
Fig.2.6 Using the Ring Guide on the UV light source
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