Help with Unknown Hallmark on Danish?? Brooch

[cjnps56]

I have a large brooch with an unknown hallmark on the back. It is a letter T with a C or G imposed on it. The top of the C or G goes over the stem of the T and the bottom of the C or G crosses under the stem of the T. It is also marked 826S which leads me to believe it is an early Danish piece. Does anyone know this hallmark? Any help will be appreciated.

[cjnps56]

Here is a pic of the front of the brooch.