The ASBL Sherlock Holmes 2.0 is a portable ultraviolet transmission instrument manufactured by ASBL (Applied Science for Better Life) and designed to screen diamonds for Type IIa nitrogen characteristics. Because Type IIa diamonds — those containing negligible quantities of nitrogen — transmit shortwave ultraviolet light rather than absorbing it, a simple UV transmission test provides a rapid, non-destructive first-stage indicator that a stone warrants closer investigation. The device is widely used in gem-trading centres and laboratory intake workflows as a triage tool before more definitive spectroscopic analysis is performed.

Scientific basis

Diamond classification by nitrogen content underpins the instrument's utility. The great majority of natural diamonds belong to Type Ia, in which nitrogen atoms occur in aggregated clusters (A- and B-centres) within the crystal lattice. These aggregates absorb ultraviolet radiation strongly, rendering Type Ia stones opaque to UV wavelengths below approximately 330 nm. Type IIa diamonds, by contrast, contain nitrogen at levels below the detection threshold of infrared spectroscopy — typically fewer than a few parts per million — and consequently transmit shortwave UV with relative ease.

The Sherlock Holmes 2.0 exploits this distinction by illuminating a stone with UV light at a controlled wavelength and detecting whether transmission occurs. A positive result — UV transmission — flags the stone as potentially Type IIa, prompting referral for infrared or Raman spectroscopy to confirm identity and detect any treatments.

Relevance to laboratory-grown and treated diamonds

Although Type IIa stones represent fewer than two per cent of natural diamonds, they constitute a substantially higher proportion of laboratory-grown diamonds produced by both the high-pressure, high-temperature (HPHT) and chemical vapour deposition (CVD) methods. CVD diamonds in particular are overwhelmingly Type IIa, as the growth process does not readily incorporate nitrogen unless it is deliberately introduced. HPHT-grown diamonds are more commonly Type Ib (single substitutional nitrogen) or Type IIa depending on growth conditions.

Certain treatments also produce or are associated with Type IIa characteristics: HPHT annealing of brown Type IIa natural diamonds to improve colour is a well-documented procedure, and the resulting stones retain their UV-transparent signature. A UV transmission result therefore does not distinguish between a natural Type IIa diamond, a treated natural diamond, and a laboratory-grown diamond — it merely identifies that the stone falls outside the Type Ia majority and requires further examination.

Instrument design and use

The Sherlock Holmes 2.0 is designed for bench use in trading and grading environments rather than as a research-grade spectrometer. Its operation is straightforward: the stone is placed in the instrument's sample port, UV light is directed through the table or another facet, and a detector on the opposite side registers transmission or absorption. Results are typically indicated by a simple pass/fail or colour-coded readout. The instrument accommodates a range of stone sizes and can be used on mounted as well as loose diamonds, though loose stones generally yield cleaner readings.

As a screening device, the Sherlock Holmes 2.0 is most valuable for its speed and accessibility. In high-volume trading environments — parcel sorting, melee screening, intake at smaller laboratories — it allows staff to rapidly separate the small fraction of UV-transparent stones from the Type Ia majority, directing only those flagged stones toward more resource-intensive testing such as Fourier-transform infrared (FTIR) spectroscopy, photoluminescence (PL) spectroscopy, or submission to a major gemmological laboratory.

Limitations

The instrument's principal limitation is that it identifies a category, not an identity. A positive UV transmission result narrows the field considerably but cannot, by itself, confirm whether a stone is natural, HPHT-treated, or laboratory-grown. Additionally, some Type IIb diamonds (which contain boron rather than nitrogen and are typically blue) will also transmit UV, and certain rare Type Ib stones may produce ambiguous readings. The device is not a substitute for FTIR or PL spectroscopy, and any stone flagged by UV transmission screening should be referred to a qualified gemmological laboratory — such as GIA, Gübelin, SSEF, or Lotus Gemology — before conclusions are drawn about its origin or treatment status.

Melee parcels present a particular challenge: a single UV-transmitting stone among hundreds of Type Ia goods may indicate the presence of a laboratory-grown or treated stone, but confirming which stone triggered the result requires individual re-testing and subsequent spectroscopic verification.

Place in the screening workflow

The Sherlock Holmes 2.0 occupies the first tier of a multi-instrument screening protocol that has become standard practice in responsible diamond trading since the proliferation of gem-quality CVD and HPHT laboratory-grown diamonds from approximately 2015 onward. Instruments such as the De Beers Group's DiamondView, the GIA iD100, and the HRD Antwerp D-Screen address complementary aspects of diamond identification; the ASBL device's role is specifically the rapid, low-cost segregation of UV-transparent stones for onward testing. Used within this workflow, it represents a practical and cost-effective contribution to diamond disclosure and consumer protection.