In AU, there should be luster evident across much of the coin. In EF-40, there should be traces of luster hiding in the protected corners. Discerning the luster on a toned circulated coin from pictures can be difficult. On these pictures, the luster comes across more like a "glow." On the very first picture, look at star 1 (bottom star on the left side) - see that glow around the star? That is luster. On the second picture, notice now that the angle of the lights has changed. You now see that "glow" around the 18 of the date. The luster appears to be quite strong on the obverse, and even stronger on the reverse. It all comes in knowing how to interpret the pictures. In the open fields, however, you see that the luster has worn down to smooth fields. If you were to view this coin in hand, I'm guessing you'd have no problem at all understanding the luster on this coin
I'm looking hard, looking hard, looking hard....Nope, I guess I can convince myself I see what you see but I don't. I accept that I need more exposure and concede your points. There's a book out there about grading coins from photographs - any value to that book?
That is a good book, but it won't help with this particular issue. Tomorrow, I'll get one of my EF Bust halves and make a gif to show you the luster. It's a lot easier to see it in motion.
I think this coin is a good example of what you’re discussing... Daylight: Lamps: Video of cartwheel: https://www.instagram.com/p/B4-44MwgV6Z/?igshid=hero7l6wb5j3 The OP coin is a significantly higher grade than this half, but hopefully this helps as a frame of reference.
From the images, I would call it a 53. It's tough to see luster past the toning. Here it is along with a few others.
Wow, this coin has significantly more wear than I'd expect for a 58. I debated 53 or 55, and ultimately went with 53 based on how much wear I saw. This is an incredibly attractive coin, but I consider it overgraded at 58.
I agree but it's about normal for how PCGS grades these things. Check out this link to CoinFacts images. I'll never understand it. Pretty seems to get a few extra points. https://www.pcgs.com/coinfacts/coin/1830-50c-large-0/images/6157
Lets see if this helps. This is an 1826 graded EF-45 by PCGS. This is one of my favorite coins, partly because the luster is so bold. In the still picture, look especially at the glow around the date, the stars on the left, and the area behind her head. That "glow" is luster. If you were to hold that in hand and rotate it under the light, you'd see it move just like on an UNC coin. However, I can't make the coin move..... Unless I use a gif or video. Maybe this will help illustrate? Now, with the moving light the behavior of the luster should be a little clearer. Notice as I move the light, the luster is changing. It has a trace of the cartwheel effect. However, you should also see that the open fields don't have any luster remaining. The luster is only in the more protected areas around the devices. The easiest place to see the is in the left obverse fields, in front of her face. The luster absolutely must be present for a coin to grade AU. This coin, honestly, has the luster of a strong AU - but there is too much wear for it to be AU. Even as low as EF-40, it is expected that there should be traces of luster remaining in the protected areas. I hope this helps you understand luster on a circulated coin a bit better.
Physics-Fan3.14, the luster is obvious even to me on your 1826 in both still and GIF views. And I agree that luster is a necessary requirement for an AU designation. But I'm not sure luster is a necessary ingredient for a XF designation, although it may certainly be present. In other words, to be AU it must have some luster but to be EF it does not have to have any luster. Anyway, I greatly appreciate the tutorial and I would have responded earlier but I had to retrieve my 95-year old mother from the hospital and take her back to the assisted living facility. I will take your points and confer with a coin club buddy who is an avid Bust Half Nut (about 250 varieties) and see where he stands on this topic. And thanks to Larry for sharing his lovely coins.
I was AU53. I was thinking TPG was AU55. AU58 is just...not correct. I like the coin, and many of the others shown in this thread. Pretty.