Thanking Dr. Brad Setser

Estimating the Currency Composition of India's Forex Reserves:
The composition of india’s reserves can be inferred, in very broad terms, from the scale of the valuation gains that india reports on a quarterly basis in a document put out by the RBI called something like sources of accretion to the foreign exchange reserves. the split between currencies in the SDR basket and other currencies is also disclosed as part of the data india discloses on its reserves through the imf (see the reserves data on india’s imf country page)