Author Topic: Are 39.75mm Diameter and 2.7mm Rim Thickness Within Empire Era Crown Dimensions?  (Read 2268 times)

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Offline TomG

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Hello,

Are 39.75mm diameter and 2.7mm rim thickness within normal China Empire era crown dimensions?
Two Chinese empire era silver crown coins were purchased on the basis of photographs with soft focus. Measurements after their arrival are:

Chihli 7 Mace and 2 Candareens (7M+2C) 1903 Y-73.1
26.69g (26.7g reference)
39.73mm diameter (39mm reference)
2.70mm rim thickness (2mm reference)

Empire Dollar (1 Yuan) 1911 Y-31
26.71g (26.9g reference)
39.75mm diameter (39.25mm reference)
2.73mm rim thickness (2.5mm reference)


Offline SANDAC

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The reverse of Y31 is in better focus and I see a number of small "blisters", 5 of them are pointed out in red arrows in the attached photo.  Are these blisters real? They are worrisome.

Offline TomG

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Hello Sandac,

Thank you for your observations. Whether the coins are authentic does interest me. The blister at eight o'clock is the only really raised spot. The rest of the areas are reflections, I think from wear scratches.

Perhaps some member(s) can tell me what are their corresponding specimen diameter and rim thickness measurements. These are the first Imperial and Chihli dollar specimens I've run across. Are the 39.75mm diameter and 2.73mm rim thickness typical caliper-measured values for these coins?

Offline TomG

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Hello,

A search of web pages, cites a typical China crown diameter of 39.0mm, with an unknown number of significant digits or decimal precision. At this point, the 39.75mm diameter coupled with a 2.7mm rim thickness, indicate both coins are over-sized replicas. They might contain silver but at a fineness below 0.900 weight fraction, hence the slightly over-sized dimensions are needed to reach weight specifications.

A specific gravity measurement will be helpful but an analytical scale is not currently available to me. My trusty analog balance will need to be set up with a tare counter weight for the water immersion support during the procedure.

The face and edge details appear better than the usual replicas but Sandac noted at least one visible blister. Possibly more are hidden in the dark verdigris areas. But there is still time for a refund request.


Offline SANDAC

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I have a Y-31 and Y-73.1 as posted here http://china-mint.info/forum/index.php?topic=3329.0
The weight of Y-31 is 26.73g and Y-73.1 is 26.39.  Both of them were subsequently slabed by PCGS as genuine so I can't make thickness measurement now.  There is a rim picture of the Y-31 in that thread.  
For your reference, I made animated overlays of the Y31 and Y73.1.  Download the images and open them use an internet browser.  images will alternate between your coin and my coin every 2 seconds.

Offline TomG

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Hello Sandac,

Thank you for the animated gif files. They provide additional comparison information about the coins in question.

Offline TomG

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Hello,

The seller of a 1903 Chihli dollar with period after "...YANG", eBay item 121794573903, measures the coin at 39.9mm diameter, 2.4mm rim thickness and 26.7g weight!

Offline dragondollar

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Hello, in my opinion both coins are good quality fakes (likely made of a a low silver content alloy, compensated by the increased diameter and thickness, and sporting rather decent artificial aging!). The Y31 was made with a very popular fake die, which can be easily identified by the missing scales within the whiskers of the dragon, and the wrong relief of its nose and tongue.

Offline TomG

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Good Morning Dragon Dollar,

Thank you for your reply. Although the coins' authenticity disappoints me, I appreciate that you took the time to evaluate the situation with your expertise and analyses. I lack experience to detect visual design discrepancies and thank you for educating me. I recall your 18 November 2011 blog advice to be cautious of cleaned 1911 China Empire dollars, Y-31, because of possible tooled placement of a period on earlier minted coins.
http://www.dragondollar.com/coins/china-empire/the-most-popular-chinese-silver-dollar/

The third eBay auction coin in the China-Mint Info forum thread is an example with a 39.9mm diameter and 2.4mm rim thickness. Discrepant dimensions of that 1903 Chihli dollar with period after "...YANG" exceed published reference values. How much is too much or too little when evaluating such coins? Thank you again.