A GBD that hits $500 is a rare occurrence. I've never seen this brand with a 9k gold cap, or a Prehistoric this old. The cap has to be original, right? The stem does not look like a 1920's button.
This is an incredible rare GBD and quite the historical pipe as well! This may well be one of the first they ever made, hard to say if there are any earlier ones as they would need to have either silver or gold like this one hallmarked.
www.ebay.com
View attachment 291524
And this one came back to the seller. It hit $344 the first time, now $285.
U.S. Pat 2001612. US Pat 2001612. Virgin Briar. This pipe has been smoked and will need to be cleaned. 3 part C logo marked on stem. Made in England.
www.ebay.com