How the gram price is derived
Although New Zealand shops quote per gram, the global market quotes gold in US dollars per troy ounce. One troy ounce equals exactly 31.1034768 grams, so the pure gold (24K) gram price is the ounce price divided by 31.1034768, converted to NZD at the live exchange rate. Lower purities are then a simple multiplication: 22K/916 is the 24K gram price × 0.9167, and 18K is × 0.75.
New Zealand has no domestic gold exchange; dealers in Auckland and Wellington price directly from the international USD spot market converted at the live NZD/USD rate, quoting per ounce, gram and kilogram.