It's a silver coin with a gold gilded B. The title is spot on.
Fair question, fair answer 
I didn't realise people modified their coins.For clarification, this is an All-Silver round, not an All-Silver with Gold Trim round.
Some people might be mislead by this.
Nobody modified this coin.
You are the only person stating that it has "Gold Trim"
The title clearly states "Silver Round /w Gold B".
EDIT - My mistake, I got completely mixed up with 2012/2013 coins. I guess spotcoins.com isn't reliable either as it lists this address as All-Silver.
Ok, let's not get heated about this.
I presumed that these particular 2012 Casascius coins were either All Silver (of which ~1300 exist) OR All Silver w/ Gold Trim (Gold edge + Gold BTC) (of which ~483 exist)
If the coin is indeed the latter, I have learned something new and I apologise. But it doesn't explain why it is listed as All-Silver on various sites.
Otherwise, I would argue it is modified, as it is no longer All-Silver, as provided by Casascius...