Tuesday, October 30, 2018

Laser cleaning of ancient coins

Briefly noted: An 8-year-old paper by Eleni Drakaki, Andreas Karydas, et al: “Evaluation of laser cleaning of ancient Greek, Roman and Byzantine coins”. Successful results are claimed, sometimes in conjunction with mechanical cleaning.

The article is a followup to an earlier paper, “Laser cleaning on Roman coins”. The image for this post comes from the first paper.

Monday, September 24, 2018

Three-dimensional reconstruction of Roman coins from photometric image sets

Three-dimensional reconstruction of Roman coins from photometric image sets”, a 2017 Journal of Electronic Imaging paper by Lindsay MacDonald, Vera Moitinho de Almeida, and Mona Hess.

The present study combined two datasets representing the surface topography of the two Faustina coins (Fig. 1). First, they were scanned by a 3-D color laser scanner, producing a point cloud of the surface shape. Second, they were photographed in an illumination dome with directional lighting. The two representations were combined to produce a digital elevation map (DEM) of each coin with the accuracy of the scanner and the fine detail of the photography.

Tuesday, September 18, 2018

The Insane Million Maker Master Counterfeiter

Good documentary storytelling on counterfeiting: Snap Judgement recently made a 22 minute segment about Frank Bourassa, a Canadian who counterfeited a quarter of a billion US dollars in twenties in 2009.

I calculate that $200,000,000 in $20 bills would weight 10 tons and would completely fill a 12' moving van.

Friday, September 07, 2018

NGC population reports for graded ancient coins

Catalogers of high grade modern coins often boast about coins having only a few specimens, or even no specimens, known in a higher grade.

Ancient coin catalogers will sometimes say "finest known" but they rarely say things like "only a population of 43 coins better".

On NGC's slab verification pages, for example https://www.ngccoin.com/certlookup/4629247-016/NGCAncients/, there are no population reports comparable to modern coins. That page says "Total Graded by NGC: Not Available".

Yet I noticed the Heritage Auctions web now includes NGC Ancients population reports. I noticed this watching their Long Beach auction yesterday. Here is an example from a recent Heritage online-only auction: https://coins.ha.com/itm/ancients/g...m-9h-ngc-ms-5-5-3-5-test-cut/a/231836-61011.s . The auction listing displays the slabbed population with the grade of the current lot highlighted in yellow.

Here is the owl population as of September 7th 2018:

The auction house gives an NGC population report and includes the count ranked star (= "impressive"). They don't mention "fine style" or "test cut" or the x/5 ratings. This particular lot has a huge test cut that doesn't make it into the numerical chart.

I was curious to see the single starred "Choice MS" example in the above population report. It is https://coins.ha.com/itm/greek/anci...22-gm-5h-ngc-choice-ms-5-5-5-5/a/3066-30035.s, and it sold for $36k last month.

Monday, August 27, 2018

Replica hobo nickels

Is anyone familiar with Chinese hobo nickel replica maker Gyphongxin? The e-Sylum discussed Chinese hobo nickel replicas but I still meet advanced collectors who do not know the scope of it.

I purchased the "hobo dime" above with the Medusa skull design last year. It looks like a 1916-D. Often the creations of the artist (or artists?) "Gyphongxin" duplicate award winning hobo nickels but I haven't found the prototype for this one. A store on Alibaba.com is selling these for $1.70 and they say they have 9837 pieces available. The seller also has one with a 1916-S reverse with 9995 available.

In hand the coins don't look particularly great. Other Chinese replicas do look great. I recommend anyone interested in the Chinese replica coin production quality listen to Charles Morgan interview Beth Deisher on the CoinWeek podcast.

There is a new wrinkle in how the coins are being shipped. The half-dollar at the top of the page sold on eBay for $4 with free shipping. It shipped from China to the nation of Georgia. (Not the US state, the former Soviet republic.) A different shipper slapped a sticker with a return address in Tbilisi over the first sticker. This process caused the replica to take six weeks to arrive. Why is the seller is willing to pay for double postage and send the coin around the world the long way? I suspect US Customs authorities are looking for and stopping these replicas.

I recommend everyone check out this Alibaba.com store. Perhaps the ancient Greek and Roman coins won't fool you. Perhaps the US coins or the world silver won't fool you. There are a few things in this store that look very good in a photo and sell for a dollar or two.

Friday, August 17, 2018

The Feather Heist

Good reporting on museum security: This American Life recently made an hourlong episode about the 2009 smash-and-grab burglary at the Natural History Museum, London. Bird carcasses and feathers worth more than $1,000,000 on the fly-fishing black market were stolen. Some have been recovered.