A few testing laboratories in Kanchipuram provide this service. This is what this portal has to say about the testing method:
In order to build the confidence and credibility among the customers and in the industry about the quality of zari in silk fabrics, testing is very important and much required. Hitherto, for testing metal contents in zari, destructive method of testing has been carried out. Now, the testing of zari samples and zari made fabric are carried out by Non-destructive testing (XRF Analyser), which is a unique one. The technical know-how of the project was jointly developed by Technology Information, Forecasting and Assessment Councils (TIFAC) and Tamil Nadu Zari with the guidance of the Indira Gandhi Centre for Atomic Research (IGCAR, Kalpakkam).
The Zari is sold in terms of MARC. Weight of one marc is 242 grams. The composition of the marc is indicated below: -
SILVER 55 to 57%
SILK 22 to 24%
GOLD 0.59 to 0.60%
COPPER 20 to 22%
RAW MATERIALS
The required raw materials for the production of the gold zari are:-
Ø Silver wire - 76 to 77%
Ø Silk - 13 X 15 denier
Ø Gold - 24 carat.