Are silk dome tweeters actually silk?

Is the material they are made of genuine silk or is that just the type of 'weave' they do ? For example with YG Acoustics.
I always believed that it was actual treated silk.
If it was not made of silk it would be called a soft dome tweeter. Yes it is silk!
That would still be called a soft dome tweeter.
Yes, it is REAL silk and the reason they never sound bright.
I talked to YG Acoustics and they said their billet dome tweeter is silk with a metal frame, but when pressing them they state its not real silk its synthetic polyester.
 I see no mention of silk with their billet dome tweeter. Where did you get that information from?