VVS1 and VVS2 are known to be types of diamond clarity. Some people are very particular about the diamonds that they get. They want to make sure that they will get quality diamonds. The VVS diamond is already known to be a high grade, but the VVS2 has more inclusions as compared to the VVS1. The VVS2 is also priced higher because this type of diamond is harder to come by.
They tend to be rarer as compared to the other diamonds that can be found right now. Some people are willing to pay the premium price to get this type of diamond while others are perfectly happy with diamonds that have less clarity because they are still diamonds anyway.