The steepest crown angle I would suggest is 35.5. And that must be paired with a 40.6 pavilion angle. That being said, I think only diamond 1 & 2 is worth to consider.. and that is just for a start. You still need to see how well cut is the diamond. A well-cut diamond will exhibit Hearts & Arrows phenomenal. So two things - Proportions and Cutting precision is the thing you should focus on.

For example this one: https://www.whiteflash.com/loose-diamonds/r...id=myengringexp (affiliate link). This diamond's cut is not bad, but not the best. It has some dark areas in the ASET image. The Hearts are also not as good, but already better than a lot of diamonds. So for your budget, I would buy this anytime rather than anything listed above because if I can't see the real thing or to view the accuracy of the cutting precision, I would play safe.

First one, 41.4 pavilion guarantee won't work nicely.

Second diamond, looks better. Followed by third diamond.

As far as ZCOVA is concerned, I highly recommend you to consult their sales consultant directly as what they listed on their website is lesser than what they can actually get. Zi Yin (their co-founder) is a GIA graduate gemologist, so he can assist you well.

Besides that, if you are comfortable buying overseas, you can consider:

Use Coupon Code: JUNE1910 to save 10% (this 10% has already include 3% wire discount). So I will just use full price - 10% for easier calculation. This discount is applicable to their standard signature line, so in this case, I would prefer to get their signature line to maximize on savings.

https://www.briangavindiamonds.com/diamonds...?a_aid=myengexp (affiliate link). Using the full price - 10% = RM 15255.65 - 10% = RM 13730.09.
https://www.briangavindiamonds.com/diamonds...?a_aid=myengexp (affiliate link). Using the full price - 10% = RM 17033.08 - 10% = RM 15329.77.

Exchange rate provided by: https://transfer.moneymatch.co/

Try to ask for free shipping as they don't come free by default.