Stempelglanz (German Coin Grade)

I read on Wikipedia that the German grade of Stempelglanz (STGL or Stgl.) is equivalent to a Sheldon grade in the 65-69 range. I searched through this forum and the posts from German members suggest that Wikipedia has it right.

Here are my questions:

1) What are the best English descriptive phrases for Stempelglanz ?

Given the correspondence to Sheldon grades 65-69, I'm thinking 'gem uncirculated' would be the best English equivalent. (With the understanding that descriptive phrases for coin grades are often used to sell coins at inflated prices in the United States.)

2) What are the best literal translation(s) for Stempelglanz?

I tried seven online translation programs using the aggregator, Lexilogos and the English translations for Stempelglanz were:

mint state
stamp brilliancy
stamp gloss
stamp shine
uncirculated

This made me wonder if Stempelglanz is a grading term for stamp collectors, or if it has more to do with stempel - to stamp, to postmark, to hallmark? (From Reverso, an online translator.)