Carat (ct) is a unit used to measure the purity of gold. Pure gold, also known as 24-carat gold, is very soft and malleable. Therefore, for jewelry making, it's usually alloyed with other metals ...
Yes, gold rates may vary slightly between jewelers due to making charges and purity levels. The rate for 24k gold is higher than 22k gold because of its higher purity (99.9% vs. 91.6%).