susiegrneyes
Shiny_Rock
- Joined
- Jan 4, 2008
- Messages
- 302
I believe SI AV stands for SI Average, you can see it spelled out with this stone's listing: https://www.hopediamonds.com.au/product/argyle-round-diamond-0-13-ct-9p/
Maybe you're on the right track in thinking that below a certain ct weight, they're just using a general "SI" grade, vs. breaking out into SI1 and SI2.
Also paging @Rockdiamond who might be able to help.
elizabethess