The attribution process — open, structured, reviewed annually.
The atlas's working methodology document is open and downloadable. The full version is eleven pages with appendices; the page that follows summarises the working method as it stands after the March 2026 revision. The document has been revised six times since the atlas's founding; the change log is available in the appendix to the downloadable version.
Stage one — photographic plate.
Every specimen entered into the catalogue is photographed in the editorial light room at the Ismailia office using a Phase One IQ4 100MP back on a calibrated copy stand. Lighting is two Broncolor Picolite heads at 45 degrees, balanced to 5500K, against a colour-calibrated grey background and a Pantone-checker reference at the edge of each frame. The colour-calibration reference has been the same physical card since 2014 to preserve plate-to-plate consistency. Obverse, reverse and edge (where the specimen permits) are photographed; the obverse and reverse are the published plates and the edge image is held in the editorial archive. Image files are stored as 16-bit TIFF originals and published as colour-managed JPEG at 1800 pixels longest dimension.
Stage two — physical measurement.
Weight is recorded on an Adam Equipment NBL-214i analytical balance, calibrated weekly against a 10 g reference standard, accurate to 0.01 g. Diameter is recorded at four cardinal axes (12-3-6-9 o'clock) using a Mitutoyo digital calliper accurate to 0.01 mm; the catalogue records the four readings and the mean. Die axis is recorded against a magnetic alignment jig built for the office in 2016, accurate to within 5 degrees. For scarabs and seals, length and width along the longitudinal and transverse axes are recorded; height is recorded against the maximum point of the back curve. Specimens that cannot be measured for physical reasons — fragments, deeply oxidised pieces, fused conglomerates — are flagged and the photographic plate is the only quantitative record.
Stage three — reference attribution.
The specimen is compared against the period's standard reference catalogue: Svoronos and Mørkholm for Ptolemaic, Burnett-Amandry-Ripollès (RPC) for Roman provincial, Goodacre and Sear for Byzantine, Walker for Arab-Byzantine transitional, Album for early Islamic, Lane-Poole-Balog for Fatimid, Tufnell-Mlinar with Petrie cross-reference for Pharaonic scarabs, Boardman-Vollenweider for cylinder seals. The lead editor for the period writes a draft attribution with the catalogue number, variant suffix (where applicable), date range (within a decade where possible), mint reading, monogram or year-mark readings, and any diagnostic notes that bear on the attribution. The draft is filed in the editorial system with the specimen number.
Stage four — two-editor sign-off.
The draft attribution is reviewed by a second editor — usually a colleague with adjacent period expertise. The reviewer's role is genuine adversarial review: to find any reason to reject or amend the draft attribution. If the reviewer agrees, both editors countersign and the specimen enters the catalogue. If the reviewer disagrees, the dispute is documented in writing; either the draft is amended and re-signed, or the disagreement is recorded openly in the catalogue with each editor's argument. Disputed attributions account for approximately one in twelve catalogue entries; the disputed status is itself the catalogue's most academically useful record.
Provenance documentation.
Every specimen must have a documented provenance line — at minimum the dealer or institution from which it came, ideally back further. Specimens with documented pre-1970 provenance enter the catalogue without further question. Specimens without pre-1970 provenance — the post-1970 cohort — are entered only if the post-1970 provenance is itself well-documented and traceable through legitimate channels. Specimens with no documented provenance at all do not enter the catalogue regardless of their numismatic interest; this is the atlas's strictest single rule and has eliminated approximately three hundred and twenty candidate specimens since 2014.
Forgery detection.
The atlas's forgery-detection process is a structured sub-routine within the attribution chain. Where a specimen presents diagnostic features inconsistent with the proposed attribution — wrong weight outside the expected range, wrong fineness, wrong style for the period, characteristic die-pressure indicators of pressing rather than striking, surface chemistry inconsistent with the period's typical production — the specimen is flagged and forwarded to forgery review. Forgery review involves comparison against the atlas's reference set of forty-one identified modern forgeries, against any documented diagnostic features of the relevant period's known forgery workshops (Beirut 1970s-80s, Damascus 1990s, Istanbul 1990s-2000s, and the more recent Eastern European workshops of the 2010s), and against the specimen's photographic plate at high magnification. Confirmed forgeries enter the forgery register, not the main catalogue.
The corrections cycle.
Corrections to published attributions are issued in writing within ninety days of confirmation. The correction is published in the next monthly bulletin, with a separate three-line notice if the attribution has been used in any external publication or seminar. The quarterly corrections register consolidates the bulletin corrections. One hundred and forty-three corrections have been issued since 2014; the rate has fallen from roughly twenty per year in the early years to approximately seven per year in the past three years, reflecting both improved methodology and the accumulating reference base.
The annual board review.
The methodology document is reviewed annually at the June board meeting. The 2026 revision tightened the diagnostic threshold for the Saite-revival scarab attribution, added the underwater-recovery protocols for the Heracleion-Thonis cylinder seals, and updated the weight-balance calibration record. Earlier revisions added the cylinder-seal corpus in 2021, the forgery register format in 2018, the hoard-report protocol in 2017 and the original two-editor sign-off in 2015. The next scheduled review is June 2027.
The methodology is applied uniformly across all five catalogue files: Ptolemaic, Roman, Byzantine and Fatimid, scarab seals and cylinder seals, and to the annual hoard reports. Readers with attribution challenges or suggested improvements to the methodology should write to the editorial board through the contact form marking the topic accordingly.