First sale invoice requirement ensures excisable jewellery sales are invoiced and manufactured value separated for duty calculation. No excisable jewellery shall be first sold from registered premises except under a first sale invoice, signed and serially numbered, showing registration number, consignee, description, classification, date of removal, and separate values for manufactured and traded articles to compute excise duty; invoices must be in duplicate (original for buyer, duplicate for assessee) and digital signature rules from the Central Excise Rules, 2002 apply mutatis mutandis.