H&A does not mean the diamond will look good, it can have them but be bad proportions.
A diamond with fair symmetry and good proportions will out perform it.
A diamond with ex prop's and H&A's will be best.
AGS certed diamonds cost more because the tolerances to acheive the AGS 0 proportions and symmetry grading are tighter, but not all AGS 0 diamonds are great proportions.
You raise a GREAT question...one I stumbled across myself when I was searching for my soon to be fiance's engagement ring (I purchased my rock about two weeks ago from Diamond Brokers of Florida, and had it set about a week ago).
As best I can tell, Hearts & Arrows symmetry is no better than any other *ideal* grade symmetry. In fact, it seems that because of successful marketing and emotional reasons, H&A stones can command more money. On Pricescope's tutorial about H&A symmetry it even mentions that the main reason one would want H&A as opposed to just ideal is emotional, because IT CAN'T BE DISTINGUISHED WITH THE NAKED EYE.
With that said, I must admit I purchased an H&A rock, but only because the price was comperable to other 1A & AGS 0 cuts in that carat range, and was significantly cheaper than other H&A cuts in the same carat range. Keep you eyes open for deals, because they are out there.
By the way, the rock I bought is stunning...beyond what I thought I'd be getting. Don't let H&A discourage you from buying a rock, but I wouldn't personally make a necessary characteristic of the rock you want to buy since you're typically (although not always) going to pay a little more for something you won't be able to observe.
If you intend to buy over the internet, I would suggest sticking with ideal cut grade only. While many are quick to point out(including myself) that there are other cut proportions that do produce better diamonds than certain bad ideal propotions, it seems to me that in general the AGS 0 cut *as a category* will on AVERAGE outperform lesser cut categories. If you can't see something with your eyes before purchasing, it just seems in theory a safer bet. BUT, the more I look at diamonds, the more I realize that they all are pretty darn beautiful above a certain standard. Some of the best advice people out have have given me is MAKE SURE you compare rocks with your EYES to get a feel for what is pleasing to you.
As far as AGS vs. GIA, both seem to have equally excellent standards. AGS is more expensive probably because it includes crown and pavillion angles. This is exactly why I chose AGS...those are necessary angles to get a preliminary idea of how the diamond performs on the HCA...I also found that when I got Sarin reports done on GIA rocks, those machines differed so greatly on certed info that it made me lose trust in them entirely.
Just some thoughts from a non-expert. HAVE FUN with the diamond buying purchase!!!! And educate yourself...knowledge is power! Hope this info helps, and that the experts don't totally disagree with me (lol)! Take care!
If you search for diamonds with AGS 0 grading and THEN compare their stats with my AGA Cut Class charts, you will find that round stones with no parameters below the 1B rating will all look and perform very well. The ones that are all in the 1A rating will be among the very best and probably among the most costly, although that may be only a nominal difference in actual dollars.
You may find a few AGS 1 rated diamonds that also will perform just as well or even better than an AGS 0 cut stone. This is a fault in the AGS system that is being worked on and not a universal problem. It is limited in scope. Those AGS 1 graded stones that find themselves within the AGA 1B range, though relatively rare, will also be very good performers.
I'd tell you to search for AGA graded stones on the Internet, but because we do little of this major work, that would be fruitless. However, once you have the parameters that the GIA does not provide such as found on AGS Diamond reports, then using the AGA Cut Class charts becomes a very easy task to analyze what is likely to be found when you really get to see the diamond yourself.
In essence, the ability to predict a fine appearance amounts to a revolution in the ability to purchase a diamond sight unseen with a high degree of confidence.
Hey thats great advice me! How about if you don't mind to read in the forum that I replied to all. It show GIA certified. What do u think of this stone? I decide to choose GIA certified. I hope I trust to Jewlery zone website . I am very slow to buy because I need to make very sure of this stone and not RIP me off . Please comment ...
Hold it! Why are you saying this? You didn't even know what the crown and pavillion angle or percentage yet.. I assume it suppose to be very good but I will get the info from them about Pavillion and Crown information for you but I could not buy this stone till I can bring it to the appraiser for sarin report. Thats the hard part for me to buy or not...
I want increase the quality of diamond cut, and reduce the number of bad cut diamonds produced and sold. It has been a bit of a crusade for a few years.