IS 2112 is the Indian Standard, published by the Bureau of Indian Standards (BIS), that prescribes the classification system for natural diamonds by colour and clarity. It works alongside the related standard IS 1417, which covers diamond grading and nomenclature more broadly, and provides the detailed scales and definitions used by Indian laboratories and traders to describe a polished diamond's appearance for trade and retail purposes.

Colour classification

The colour scale prescribed by IS 2112 follows international practice in dividing the colourless to yellow range into letter or numerical grades, broadly corresponding to the GIA D-to-Z scale familiar in the international trade. The standard also defines the boundary at which a stone enters the fancy-coloured category and prescribes the qualifying language, where a saturated colour would otherwise fall outside the standard scale. Disclosure of treatments affecting colour is required.

Clarity classification

Clarity grading under IS 2112 follows the conventional system of distinguishing flawless, internally flawless, very very slightly included, very slightly included, slightly included, and included grades, with subdivisions corresponding to the international IF, VVS, VS, SI, and I categories. The standard prescribes the magnification and lighting conditions under which clarity grading is to be performed, generally ten-times magnification under standardised diffuse lighting, and the defining characteristics of each clarity grade.

Application

IS 2112 is applied by Indian laboratories, retailers, and exporters, and serves as the reference document for hallmarking and quality-mark schemes operated under BIS authority. Indian retail tags often carry IS 2112-aligned colour and clarity grades alongside any laboratory report grades issued by GIA, IGI, HRD, or other major laboratories, providing the consumer with both an internal grade and a recognised international grade.

The standard is voluntary unless made mandatory by government notification under the BIS Act, but compliance is universal among certified laboratories and accredited retailers in India. Trade buyers handling Indian-graded stones for export, particularly those shipped from Surat or Mumbai cutting centres, will encounter IS 2112 grades on commercial documentation and internal grading sheets.

Relationship to international standards

IS 2112 is broadly harmonised with the colour and clarity grading scales used by GIA and aligned international laboratories, with some differences in language and grade boundary handling. CIBJO standards on diamond grading are referenced in the harmonisation discussion, and Indian standards are progressively aligned with ISO 24016 on diamond grading and disclosure as that international standard has matured.