Presidium SDS II Review: UV Screening After Diamond Identification

Short version: the Presidium Synthetic Diamond Screener II (SDS II) makes sense as a conditional deep-UV diamond-type screening and referral companion for an already confirmed, colorless D–J diamond.[1][2] It is not a microscope substitute, simulant tester, authentication certificate, origin report, or valuation instrument. The selected marketplace record identifies SDS II, ASIN B01GILXW0O; confirm the seller’s supplied revision and accessories rather than treating the maker’s handbook as a shipment guarantee.[3]

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What question it can narrow

The maker describes deep-UV absorption/transmittance: Type Ia and Type IIa diamonds absorb different amounts of UV, with Type IIa allowing more deep UV through.[1] In practical terms, this is a material-type screen after the stone is already known to be a diamond. The handbook says to ascertain that prerequisite first; SDS II is not the tool for identifying an unknown simulant.[2]

A blue “Natural” indication should be read narrowly as high absorption typical of the usual colorless Type Ia range, not proof of mined origin, natural growth, treatment history, identity, or value. A red “Type IIa Diamond” indication is a referral flag: Type IIa can include laboratory-grown material and can also occur in natural diamonds. It does not identify CVD versus HPHT, prove laboratory origin, or establish process. Follow the maker’s further-testing boundary rather than turning either color into a certificate.[1][2]

Fit before buying

Confirm the starting point: you already have a confirmed diamond and want a UV type-screening lane alongside visual microscopy. Keep the microscope for inclusions, surface features, and photographs.
Check the stone: colorless D–J, a flat facet or surface, approximately 1.5 mm minimum width, and no more than 5 mm height. The maker page and handbook differ on an upper carat statement (>10 versus 10), so do not treat carat as a universal fit promise; the dimensional limits control.[1][2]
Check access: for a mounted stone, the setting must be open-backed with a clear, unobstructed view. A loose stone is placed table-face-down over the detector, covering it completely.[2] Skip stones outside those geometry, color, or access conditions.

What the workflow actually involves

The table faces down toward the testing area. The lever positions the UV source; the supplied 5 mm metal bar holds that source raised for successive loose-stone tests, rather than supporting the stone itself. The handbook says the source need not touch the diamond. Testing is performed with the lid closed: steady blue on Start Test indicates ready, blinking blue indicates testing, and steady white indicates completion; the handbook also documents checking the stone in at least four positions for consistent readings.[2] That is a user workflow instruction, not a promise of repeatability, accuracy, timing, stability, or calibration.

The maker describes USB as an alternative power route, not battery charging, and specifies four AAA batteries; I found no evidence that batteries are included in the exact seller shipment.[1][3] The maker’s standard package language and the handbook’s list include an adaptor, cable, case, 5 mm bar, quick guide, and QR card, but an unitemized seller revision may differ. The current maker page says “Adaptor Included,” and the handbook names the Presidium Universal Power Adaptor. These are source-attributed package descriptions, not inspection of the seller’s box.[1][2]

Skip the wrong expectation

This is not a fluorescence microscope or a photo workflow. It contributes a deep-UV reading to a prior identification workflow; it does not replace microscopy, a qualified gemological examination, or referral when the result is red, ambiguous, or inconsistent. Use the handbook’s closed-lid controls and handling instructions; this review does not establish safe UV exposure or independently tested screening performance. Page 26 ends its further-testing explanation with “laboratory-grown Type IIa diamond or a Type Ia diamond,” which is inconsistent with the main red-result explanation. Do not silently change that wording or use it as a final classification rule.[2]

Final verdict

Buy only if your work already contains confirmed colorless D–J diamonds that meet the flat-facet, width, height, detector-coverage, and open-back rules, and you want a bounded UV screening/referral companion. Skip it if you need unknown-stone identification, mined-origin proof, definitive lab-created classification, universal carat fit, or a microscope replacement. A blue result indicates the documented Type Ia-like absorption range; a red result should send the stone to further examination. Neither result is the final word.