Why 21k leads in Egypt
21k combines a high gold content (87.5%) with enough hardness for everyday jewellery, so it makes up most of what Egyptian jewellers sell, and it is the basis for pricing the gold pound.
Working out the final price of a 21k piece
Final price = (weight × gram price) + (weight × making charge) + VAT. For a 10-gram piece with EGP 150 making per gram: 63,030 + 1,500 + 90 = about EGP 64,620.
When you sell, you get weight × the buying price only; neither the making charge nor the VAT comes back.
21k versus 18k and 24k
18k (75% gold) is about EGP 900 cheaper per gram and suits modern designs, but carries more VAT per gram. 24k is pure gold and suits bars and saving more than jewellery.