My question is about security edges on British or British Commonwealth coins. I want to know what coins were struck with security edges prior to 1937. The reason I ask has to do with an article I am writing on a group of Chinese pattern coins from 1936 and 1937. The 1937 coins were actually struck at the San Francisco Mint in 1938, with normal edge reeding. Some of the 1936 dollars and half dollars, however, were struck with security edges. Supposedly the blanks for these patterns were supplied by the Royal Mint to the Shanghai Mint where the patterns were struck. What coins did the Royal Mint strike with a security edge in 1936 or earlier? I've looked through the Seaby catalogs, but they seldom mention the edges. I have three books on British Commonwealth coins, but again, almost nothing about the edges.

I don't think the USA has ever used a security edge on its coins, other than perhaps on an obscure pattern. Basically a security edge is reeded but with an indented groove in the center -- sorta like an Oreo cookie. There are variations; for example sometimes there are dots inside the groove. The idea is that a security edge prevented counterfeiting.

The Kann catalog of Chinese coins did not list the security edge coins because Kann did not own any of them at that time (1954). It was first noticed in the unreleased 2nd edition of Kalgan Shih's catalog of Chinese silver and gold coins (1951). I knew about the coins in the 1980's, but had never seen one nor a photo of the edge. The first time a photo of the security edge was published was in the June 2006 Cheng Xuan Auction in Beijing. The same auction house has another example in its current (November 2012) sale, with a photo, but the edge photo does not show up online. I was able to copy the photo from the 2006 sale, and it is attached.