Ermmm mine's insured by GIO for more than $10k though and they didn't even ask me for any proof or photos to justify that. And I can confirm it's a seperate nomination because my policy states:
General Contents: $xx,xxx
Transformers Figurine Collection: $1x,xxx
I added a couple more $k to it because I know I'll be buying more throughout the year (after I applied for it), just to cover the extras you buy. And of course I have the excel spreadsheet as well.