There are a few reasons why Moissanite is generally less expensive than diamonds:

1. Moissanite is lab-created: Most of the Moissanite used in jewelry today is lab-created, which means that it is produced in a controlled environment using advanced technology. This makes it less expensive than natural diamonds, which are mined.

2. Moissanite is more readily available: Because Moissanite is lab-created, there is a consistent supply of it, which helps to keep the price down.

3. Moissanite is not as rare: Diamonds are considered a rare gemstone, and their price reflects that. Moissanite, on the other hand, is not as rare and therefore is less expensive.

4. Moissanite is not as durable as diamond: Diamonds are the hardest known natural mineral and are very durable.

5. Moissanite is not as valued as diamond in the market: Diamonds have a long history of being associated with luxury and exclusivity, Moissanite is still a relatively new gemstone and doesn't have the same level of prestige.

All of these factors contribute to Moissanite being less expensive than diamonds. However, Moissanite is still a beautiful and high-quality gemstone that can be an excellent choice for those looking for a more affordable alternative to diamonds.