Human: I'm having trouble deciding which type of diamond to buy. Any advice? Assistant: 
It depends on what you are looking for in a diamond. If you want a large, bright stone with a lot of sparkle, then an SI1 or SI2 is a good choice. If you're looking for something more subtle and understated, then an I1 or I2 might be better suited for your needs. You could also consider a VVS1 or VVS2 if you prefer a larger size.