The AHC code — an abbreviation for Assaying and Hallmarking Centre code — was a numeric identifier assigned by the Bureau of Indian Standards (BIS) to each licensed assaying and hallmarking centre operating within India. Stamped as part of the BIS hallmark on gold and silver jewellery, the code indicated precisely which centre had tested and certified a given article. Though now superseded by the six-digit Hallmark Unique Identification (HUID) number introduced in 2021, the AHC code remains relevant to anyone assessing or authenticating Indian jewellery produced before that transition.

The BIS Hallmarking Framework

India's compulsory hallmarking programme is administered by the Bureau of Indian Standards, the national standards body established under the Bureau of Indian Standards Act. BIS hallmarking for gold jewellery was made mandatory in phases beginning in June 2021, though a voluntary scheme had existed since 2000. Under the earlier voluntary system, and during the initial mandatory phase, a compliant hallmark on a gold article comprised four components stamped in sequence:

• The BIS logo (a triangular mark)
• The purity or fineness grade (e.g., 916 for 22-carat, 750 for 18-carat)
• The AHC code — a numeric identifier for the licensed centre that conducted the assay
• The year of hallmarking, represented by a letter code

The AHC code within this sequence served as the accountability anchor: it allowed regulators, retailers, and consumers to trace a hallmarked piece back to the specific centre responsible for its certification. Each licensed centre received a unique numeric code upon accreditation by BIS, and that code was registered in BIS records alongside the centre's address, ownership, and technical credentials.

Function and Significance

In practical terms, the AHC code performed a function analogous to the assay office marks used in British and European hallmarking traditions — the anchor of Birmingham, the rose of Sheffield, or the orb of London — in that it identified the certifying body rather than the manufacturer. For a country as geographically vast as India, with jewellery production concentrated in cities such as Mumbai, Kolkata, Chennai, Jaipur, and Surat as well as in numerous smaller regional centres, a reliable centre-identification system was essential to the integrity of the hallmarking programme.

Enforcement authorities could use the AHC code to investigate complaints of mis-hallmarking or fraudulent stamping: if a piece bore a code belonging to a centre in one city but was sold by a retailer in a distant region with no documented supply relationship, that discrepancy could trigger inspection. Similarly, BIS field officers conducting market surveillance would cross-reference AHC codes against the official register of licensed centres to identify counterfeit or lapsed marks.

Limitations of the AHC System

Despite its utility, the AHC code system had structural limitations that became increasingly apparent as India's jewellery market expanded and digital governance expectations rose. The code identified only the centre, not the individual article: two physically identical pieces hallmarked at the same centre in the same year would bear indistinguishable marks, making item-level traceability impossible. This created vulnerability to fraud, since a single genuine hallmark impression could theoretically serve as a template for counterfeiting marks on unhallmarked or sub-standard goods. Consumer verification was also impractical — there was no straightforward mechanism by which an ordinary buyer could independently confirm that a given AHC code was valid and current without consulting BIS records directly.

Transition to the HUID System

In response to these limitations, BIS introduced the Hallmark Unique Identification (HUID) number as part of the mandatory hallmarking rollout that began in June 2021. The HUID is a six-character alphanumeric code, laser-inscribed on each individual article and registered in a centralised BIS digital database at the moment of hallmarking. The transition effectively replaced the four-component stamp — which included the AHC code — with a streamlined mark comprising the BIS logo, the purity grade, and the HUID.

The HUID system addresses the core weaknesses of the AHC regime in several ways. Because each code is unique to a single article and linked to a digital record, item-level traceability is achieved for the first time. Consumers can verify a piece's hallmarking status by entering the HUID into the BIS Care mobile application or the BIS website, retrieving the purity, the hallmarking centre, and the date of certification. The laser inscription is also substantially more difficult to counterfeit than a physical stamp, and any tampering is more readily detectable under magnification.

The year-of-hallmarking letter code was simultaneously discontinued under the new system, as the HUID database record captures the precise date of assay, rendering a separate year mark redundant.

Relevance to the Trade Today

For gemmologists, valuers, and jewellery professionals handling pre-2021 Indian gold jewellery, familiarity with the AHC code remains practically necessary. Estate pieces, inherited jewellery, and stock acquired before the mandatory transition will continue to circulate bearing the older four-component hallmark. Identifying and interpreting the AHC code — and cross-referencing it against BIS records where possible — is part of due diligence when assessing the provenance and certification status of such articles.

It should also be noted that the transition was not instantaneous: a grace period allowed existing hallmarked stock to be sold, and some overlap between the old and new systems occurred during 2021 and 2022. Professionals should therefore not assume that any piece bearing an AHC code is necessarily pre-2021, nor that the absence of an AHC code guarantees a post-2021 HUID mark, particularly when examining pieces that may have been re-hallmarked or that originate from regions where implementation timelines varied.

For silver jewellery and artefacts, BIS hallmarking has followed a parallel but separately phased trajectory, and the AHC code appeared in silver hallmarks under equivalent conventions before the HUID system was extended to cover silver articles as well.

Further Reading

• Bureau of Indian Standards — Hallmarking of Gold Jewellery/Artefacts
• Bureau of Indian Standards — Hallmark Unique Identification (HUID)