Gypsy said:If he wants to shop a JA, then it's a round, not an oval.
Good news is, since you get MUCH MUCH better light return in a round, you can go down in color. Which you can't with an oval.
So, here are the choices:
https://www.jamesallen.com/loose-diamonds/round-cut/0.90-carat-k-color-vvs2-clarity-excellent-cut-sku-1868075 K
https://www.jamesallen.com/loose-diamonds/round-cut/0.82-carat-j-color-vs2-clarity-excellent-cut-sku-1128375 J
https://www.jamesallen.com/loose-diamonds/round-cut/0.81-carat-h-color-si1-clarity-excellent-cut-sku-1833535 (this one needs an idealscope image because the crown is over 35)Put on hold before it gets snatched.
Any of these would be a nice choice.
I'd only do the K with an all metal solitaire.
The H gives you the most flexibility. And is personally the one I'd want. The J is lovely though, and gives you room for a nicer setting, possibly.