Extended ID: What It Adds Over Basic Identification

Primephila's identification tool comes in two levels. Basic ID is free, takes one photo of the front, and gives you a starting point. Extended ID is a deeper, paid analysis that takes three photos and looks at the physical characteristics that separate one variety of a stamp from another. Here is the practical difference.

What Basic ID gives you

From a single front photo, Basic ID returns the country, an approximate year of issue, a Primephila Reference Number, the theme or subject, and an indicative value range. It is free, it is fast, and for most stamps it is enough to tell you what you are looking at and roughly where it sits in the market. It is the right first step for sorting an accumulation or deciding what deserves a closer look.

What Extended ID adds

  • Watermark detection. Whether a watermark is present, and what it appears to be. Because the same design was often printed across several watermark periods, this is frequently the detail that decides which catalog listing a stamp belongs to.
  • Perforation estimate. An estimate of the perforation gauge read from the image, including whether the edges look compound (a different gauge horizontally and vertically).
  • Printing variety notes. Observations on the printing method and any visible variety — shifted or doubled impressions, colour differences, missing perforations, overprint anomalies.
  • Condition assessment. Gum state, hinge remnants, cancellation, thins, creases and centring, read mainly from the two back photos, together with an overall condition grade.
  • A confidence level on each finding. Every field comes with an indication of how firmly it can be read from your photos. Where the answer genuinely is not readable, it says so instead of inventing a plausible one.

That last point is the important one. Extended ID is an AI-assisted analysis of photographs, not a certificate. It is designed to tell you what it can see and to be explicit about what it cannot — which is far more useful than a confident-sounding guess. For anything you believe is a significant rarity, expert certification from a recognised philatelic body remains the only authoritative answer.

Why it needs three photos

Each of the three images carries information the others cannot.

  1. The front identifies the design, denomination, country and printing.
  2. The back under normal light shows gum, hinge remnants and cancellation soak-through — the basis of the condition assessment.
  3. The back held against a light source reveals the watermark, which is a variation in paper thickness and therefore completely invisible under normal light. There is no way to read a watermark from a front-facing photo.

Because the quality of these three images sets a hard ceiling on what the analysis can determine, it is worth following our photo guide before running an Extended ID.

How it is priced

Extended ID uses prepaid credits. You buy a credit pack once — 10 credits for €2.50 or 50 credits for €10 — and each Extended ID analysis uses one credit. Credits do not expire, and if an analysis fails on our side the credit is returned to your balance automatically. Basic ID stays free and never uses a credit.

Which one should you use

Use Basic ID to triage: to find out what a stamp is and whether it is worth more attention. Use Extended ID on the ones that matter — where a watermark or a perforation gauge could move the stamp between a common listing and a scarce one, or where you are about to list it for sale and want the condition described accurately. See the FAQ for the full details on credits, and our rare-stamp identification guide for how to check these same features by hand.