If your buying question is “diamond or moissanite?”, choose an instrument whose documented purpose includes that distinction. Gold Kings would shortlist the GemOro UltraTester 3+ for this task before the Presidium Diamond Mate A alone.
Look for the actual distinction
The Diamond Mate’s thermal method does not resolve diamond versus moissanite. The UltraTester 3+ is designed to assist with separating those materials and white sapphire.
That difference is more important than comparing the size of the display or the apparent simplicity of a demonstration.
Read the exact model’s instructions. A description such as “diamond tester” is too broad to establish which materials it can separate.
Check whether your stones are suitable
Think about the stones you actually handle: loose rounds, small mounted stones, curved surfaces or crowded settings. Access to a suitable test surface can determine whether you can make the required contact reliably.
A tiny probe is helpful only if you can place it correctly. Ask about the manufacturer’s minimum sample requirements and how it handles difficult or inconclusive cases.
A demonstration should include representative items from your expected work, not just an unusually easy sample.
Value clear signals and usable handling
Look for a result system you can read and understand while keeping the probe on the intended spot. Learn the metal-contact warning separately from the stone result.
Consider whether the grip, lighting and support arrangement work comfortably for you. Repeated slips onto a prong are a workflow problem, not a reason to accept whichever signal appears most often.
Check how the tester is maintained and what support is available if results become inconsistent.
Keep origin and grading separate
Separating a likely diamond from moissanite does not automatically establish natural origin, quality grade or value. Those questions require their own evidence.
Record the model used and the observed indication rather than turning a screening result into a broader sales claim.
Our recommendation
Choose the UltraTester 3+ when its documented sample requirements fit your work and moissanite separation is the main need. Choose the Diamond Mate A only with a clear understanding of the additional testing that remains necessary.
Compare current seller support, complete accessories and instructions before deciding on price. The right feature is the one that answers your actual question under conditions you can reproduce.
Explore the relevant products
- GemOro UltraTester 3+ Diamond, Moissanite & White Sapphire Tester
- Presidium Diamond Mate A PDMT-A Diamond Screening Tester
Check the exact model, seller, package contents and current offer on the linked product page before ordering.
Sources and further reading
- Presidium Diamond Mate specifications
- Presidium Diamond Mate manufacturer handbook
- GemOro UltraTester 3+ manual
Explore more Gold Kings buying guides.
As an Amazon Associate I earn from qualifying purchases. The product pages linked in this article contain Amazon affiliate links. This guide is based on published specifications and practical buying considerations, not a controlled hands-on product test.