I wouldn't go there John. We have collected these coins since before Americans were shooting turkeys. I see no reason to change ancient grading and start using modern US grades.
Can we translate it? lol ... like how the metric system is converted to and from the imperial system.
Can we? I have seen AU's from NGC I would grade XF, others that would grade VF, and a couple that would run gF. So what would the "translation" be for such items?
Museum replica coins are struck by machines. I think the last coin I posted above is pretty high grade and probably looks a lot like the day it was spent.
Look for coins that are interesting to you, have good centering, full readable legends, good surfaces, well struck and don't have problems such as bronze disease, tooling, and smoothing. If you can't find a coin you like with perfect centering, full legends, and surfaces that are problem free decide what you can live with. Sure maybe the obverse portrait isn't fully centered but no details are lost. Or maybe you find a coin where part of the reverse legend is off the flan but otherwise is a real stunner. In my experience and the way I keep track of my ancients - I describe the coin instead of using an abbreviation that has no quantifiable meaning. They're not like IHCs where the amount of Liberty visible determines the grade.
Have you looked at AncientJoe's site? That would answer a lot of questions. Just forget about modern grades, they just don't apply. Throw 10 ancient coins on the table in front of 10 collectors, do you have any idea how many grades you would get for each coin?
I've only been at this for a couple of years, but one of the attractions for me was the fact that there are no hard and fast rules, and that applies to grades. I don't worry about grades at all. If the coin relates a good story or otherwise evokes curiosity, looks good, and works with my budget, I buy it. Surface, centering, wear and all the other stuff mentioned on Doug's page and in this thread affect the look of the coin, but I don't worry at all about how those might combine to produce a grade.
If your ultimate concern is high grades, don't collect ancients. Ancients are about history, grade is secondary, if even that high. If you don't feel the allure of a coin that's thousands of years old regardless of its condition, you're really better off collecting something else. There are plenty of moderns that come in very high grades. I'm not saying this to be discouraging, but if grade is your highest priority, you'll always be disappointed.
Stop telling people to read Doug's pages. He obviously does not know anything or he would be selling plastic boxes. Most of his pages need updating but he does not know where to start. The grading pages really need work. I am disappointed in the lot of you for not mentioning the problem with that sample slab. IMHO (but I am no expert on expensive coins) That is a wonderful coin that I would love to have in my collection AND if I owned it I would NOT take it out of that slab. Why? Notice that line on the label "100 Greatest" no. 16. Someone told the slabbers to identify that coin as the type #16 in the highly recommended book 100 Greatest Ancient Coins by Harlan Berk. However, if you look at page 26 where we find #16 you will find that #16 is the SEA turtle not the land tortoise. Mr Berk did not list the land tortoise in the 100 and, again IMHO, also should have shown a backup land version on that page if he did not want to give it a separate number. However, I will point out that I did not write the book and each of us will have a different opinion on what the top coins are. I suspect that the slabbers just wrote on the label what they were told and did not care in the least that #16 is a different coin. For the record, I did post my 99 1/2 favorite coins (I'm quite aware that I am more than half a coin behind Mr. Berk whom I respect greatly but I wanted a lot of coins on my list). Most, but not all, of Mr. Berk's hundred are very high grade but it is not condition that made those coins special. They are wonderful in so many ways and the vast majority of modern collectors would not appreciate most of those ways. Collect ancients for a while and you may understand. For example his #90, Noah's Ark (the coin was robbed - I would have put it higher) is a corroded fine. I suspect it was the best specimen he could get an image for use on that page (100). The best example of that coin I have seen has great surfaces and less wear but it has four holes. One of our regulars here on CT once mentioned not liking his example of #73, Sulla's Dream but he keeps it partly because his is the specimen in 100 Greatest. This brings us to the question we each address in our own way. When the best known coin of a type is not perfect, can we stoop to owning it anyway? I stooped a lot in selecting my imperfect Favorites: http://www.forumancientcoins.com/dougsmith/favs.html Fewer of my 99 1/2 have any claim to being EF than fall at VG or lower. I own 100 coins that might be considered EF but most of them have no chance of making my Favorites list. My answer to your original question is VF. I feel fortunate to have VF coins if we must use the worthless letter grade system. Some of our most high minded members here have proposed a new grading system which really just formalizes what I consider to be the proper two level grading scheme: "I like it" and "I don't". If you don't like it, don't buy it. Here is another point: Enjoy your coins. If you only have them because they are high grade or high dollar and they do not move you to learn more, I strongly suggest you will be happier collecting Proof Sets.
The one place I suggest Air-tites, or something similar, is for crystallized silver coins. They are fragile and can break into pieces. The case helps limit impacts that could break a coin. My Tribute Penny is in an air-tite. You can see grains where a piece chipped from the edge of the coin. A second coin with similar issues, I did not protect until the coin broke. A 2X2 flip will not offer protection.
ancient coins do not need to be high grade and/or slabbed to be enjoyed and admired, scroll thru the ancients forum, lots of pics there, in all conditions, you will see that not all coins purchased are high grade and most are raw...
to be fair, this is what a poorly preserved hoard looks like where the coins were probably buried in a wooden box or cloth bag, or where the pot was smashed to pieces hundreds of years ago by a medieval plough. Some hoards produce bronze coins which come out of the ground unblemished, especially if still in the pot and usually from the centre of the clump.
Tortoise Stevex6 has the best method of grading, but I can't be bothered to look for the post. My coins are in trays and a case. Some are in quadrum capsules but I can take them out whenever I want. Doug's description of the slabbed tortoise and it's errors is a classic example why slabs are a load of old tosh.
@iPen / @Jwt708 You can see where I freed a coin from a slab at: https://www.cointalk.com/threads/alegandron-had-a-slam-dance.268286/page-2#post-2230730
I love Doug's post earlier, especially only buy coins YOU love. The biggest difference between ancient collectors and the "modern coin biz", (not all modern coin collectors), is we love our coins for what they ARE. We do not love them for what they are worth, or their grade, or their "condition census", or anything other nonsense. We deep down have an ingrained love of holding history in our hand, tangible proof past glory and glorious defeat.