In Birmingham the date letter changes in July up to 1974. From 1975, all Assay offices have the same date letter which changes in January. Depending upon the font used for the series of date letters, the letter i, j or l is usually omitted to avoid any possible confusion between them.

What is difference between 916 and hallmark gold?

BIS 916 gold is 22 Karat hallmarked gold, with the number 916 denoting the purity of gold in the final product. Similarly, 958 gold denotes 23 karat gold, while 750 gold denotes 18 karat gold. Simply put, 916 reflects the finesse of gold jewellery, with 91.6 grams of gold per 100 grams.