Double rings were introduced in mid April of 1906. The Diamond and Arrow logo was introduced in 1908 but it wasn't stamped on razors until around late 1914.
I'm sure you meant Single Ring for the 1906 introduction. The only reference to the introduction of the Single Ring I have is from Phillip Krumholz who places the date "About June of 1906..."
As for the diamond trademark I posted a pic of the rare ABC pocket razor with the diamond and arrow trademark impressed in the cap of the razor. The razor was made in 1909 ser# A882458. You can see the razor and ser# on Mr. Razor's site.
I don't know when the SR's were stamped because even though I have five of them they jump from 1906 with no diamond to 1915 with a diamond.
Len