I remember Bitcoin Diamond, and I actually thought it was a dead project since I never noticed any news. Now I see it is still alive.
However - Bitcointalk - no real communication in the thread. Telegram groups - only 60 or so members and no communication from the team since last year.
Coinmarketcap shows the sudden drop in value at one point.
Obviously, the team gathered some money and ran away. I could be wrong though, if I am, I apologize to the B.Diamond team.
Like you, I also think BCD is dead. I have not seen anyone mention BCD in a while. And I was quite surprised to see BCD still in the top 100 coinmarketcap list