Why there is no single answer without a karat
The gold price you see quoted in the news is for pure gold, per troy ounce. Jewellery is an alloy, so the per-gram value of a piece depends entirely on its purity. At the same spot price, one gram of 24K holds nearly three times the gold of one gram of 9K. Any page that publishes a single "gold price per gram" without naming a karat has left out half the answer, and it is the half that changes the number.
The conversion itself is simple. Divide the troy ounce price by 31.1034768 to get the price of one gram of pure gold, then multiply by the fineness: 0.375 for 9K, 0.417 for 10K, 0.585 for 14K, 0.750 for 18K, 0.875 for 21K, 0.916 for 22K.
The units gold is actually bought in
Markets quote troy ounces. Scrap buyers in the United States frequently weigh in pennyweight, one twentieth of a troy ounce or 1.5552 grams. Across India, Pakistan, Bangladesh and the Gulf, gold is bought and gifted by the tola — exactly three eighths of a troy ounce, or 11.6638 grams, and called a vori or bhori in Bangladesh. In Thailand everything is priced by the baht, and there are two of those: the bullion baht is 15.244 grams and the jewellery baht is 15.16, about half a percent apart.
Knowing which unit a quote is in matters more than it sounds. A price per pennyweight is 55% higher than the same price per gram for identical metal.
Shop price, metal price, buyer price
Three different numbers sit around the same gram of gold. The metal price is what this page shows. A jeweller selling you a 22K bangle charges that plus making charges, plus wastage, plus margin and any local tax — commonly 10 to 25% above the metal, and considerably more for intricate work. A buyer purchasing the same bangle back pays the metal price minus their margin.
Neither direction is dishonest. They are the two sides of a spread, and the useful thing is knowing where the middle sits before you stand at either counter.