LnC LoveMarque has 2 kinds of cert - IGI or IIDGR. Personally, I would prefer the one on IIDGR as it shows the actual Hearts & Arrows image. I doubt IGI has it on their cert.

D&P Estrella also has 2 kinds of cert - IGI or GIA. I think they have AGS as well, but I am not too sure. This brand of diamond is basically getting the better cut diamonds and do a rebranding of these diamonds. I have just saw a GIA Estrella in one of Diamond & Platinum branches last week.

D&P does do ring setting for loose stones. I have a forumer did their ring setting with D&P before.

I would say both D&P settings and LnC settings should be pretty nice. But this does not mean other jewellers can't do the same.

If you are located in Penang, you may want to try Frou Frou (which is on the more expensive side, starting from RM 2000 as far as I know) or iDo Jewellery (which is based in Bukit Jalil, but her hometown is in Penang I think, she travels back sometimes). There is Vanessa Diamonds too, http://venessadiamonds.com/. But I am not sure how is her price or setting, but a forumer bought his/her engagement ring there. Maybe you can drop by and have a look and see what's in-store for you.

For your budget, you can complete a 0.4ct D-F colour VS1/2 quality diamond + ring setting. Of course, I don't know what is the "x" in 0.4x, if it is a "5" and above, I believe the price will be slightly higher, but nothing too far from it.

Diamond 1 seems fine. If you can see the real diamond then see how you feel about it.

Diamond 2 I don't think that is the full GIA number.

Diamond 3 proportions I am not that conformtable as 35.5 crown angle is best paired with 40.6 pavilion. But if you can see the real thing, then it is good.

35.5 will still be bright. 35.5 is always best paired with 40.6. For other angles like 40.8, you will need to have the idealscope to see if there are any apparent light leakeges. If it is paired with 41 and above, I will forget about it. Crown and Pavilion pairing is always an inverse relationship. One shallow one steep or vice versa. 35.5 crown is a steep crown angle while 40.6 is a shallow pavilion, so it can work well if the cut is up to par. Remember that proportions is not the only factor, it is just one of the factors.

To me, for GIA, the best proportions will always be 34.5 crown and 40.8 pavilion as that is the original Tolkowsky angles. And also the safest too. Other angles can work well too, such as 34 crown and 40.8 pavilion. Today I am helping my friend to source from supplier and we find that it has the best ASET.. It even win the ASET for a 34.5 crown and 40.8 pavilion probably due to some other factors, but truth to be told, that 34.5 crown and 40.8 pavilion diamond I saw is already considered one of the top in the virtual inventory market... Just that this time the other dimaond wins. The other pairing is 35.5 crown pair with 40.6 pavilion. These are the few pairings I saw before and they work well.

For others, we will need to go case-by-case basis. But what I can say that... Pls skip anything above 41.2 pavilion.

As for the 2006 stone, I won't buy it as it may be a second hand stone or it may be so unattractive that it is still there. Unless I really like how it looks, I won't ask about it further. Of course the decision is merely yours...

My advice is try to compare with any signature stone in the stores. Signature stones usually have better proportions and hence higher price.

And HCA is really just for reference only, an actual view of the stone is more practical. With performance images like ASET and Idealscope will be best but only in dreams you may be able to get it from brick-and-mortar.

Update:
And dimaond 2 is a Lumiere stone - Hearts and Arrows brand carried by Tomei... So it is supposed to have better proportions and exhibit hearts and arrows... By right is should perform well. Try to compare it with others.