I am searching for a diamond near colorless around 1 ct or greater si1 or greater. My budget is $5700for the stone. I was shown a stone at a brick mortar store in my area the other day it was NOT certified. I was told it was 1.18ct F color I1 $4800. The stone was fairly clean looking to me (which doesn't say much) and with a loupe I noticed one imperfection a fissure? The was located at the 7 o'clock position and it looked like it would be covered by the prong other than that I couldn't really notice anything else. The store is reputable in the area and has been in business a while. My concern is how do I know if this is a deal to good to be true or should I just purchase the stone separately online? Anyone have any suggestions on stones or whether is stone is worth it?