just a note: Propworx CoA's come with a matching, numbered hologram sticker on the COA and the item. Very, very hard to fake.
Yes and no. It would be difficult to remove hologram stickers intact and transfer them to a fake prop yes, but there are securities counterfeiters who do similar things, so I'm sure someone dedicated enough could learn how. I'd imagine a little research on the net for chemical or physical removal treatments, and some practice with low-value props with the holograms, could most likely give one the skills needed. [Or perhaps as an avid viewer of the show
White Collar my imagination gets the best of me. :lol ] But in reality this is highly unlikely, since few props are valuable enough for the unscrupulous to spend that much time on, and the ones that are would be subject to high scrutiny on resale. To waste time acquiring such skills in order to risk jailtime over a few thousand dollars would be crazy. It serves as a very practical barrier to counterfeiting props, and for that Propworx's method deserves praise. Props that are directly hologrammed can't just be instantly substituted and sold with the COA from something more valuable, as I mentioned seeing done with some Premiere Props items on resale in a recent auction.
For costumes though I don't have the same faith in the Propworx holograms because they're attached to cards attached to the costumes; a tagging gun like retail clothing stores use, which could be used by a fraudster to remove and reattach the card with the hologram to an item of lesser value, is a common item. That's why it's important to closely examine costumes of value on resale, comparing details to the images on the COA or in the case of Propworx its online archive. That's another thing I have to thank Propworx for, in addition to the holograms on props: the online archive, with good resolution images of all their publicly sold props and wardrobe. I wish all the other companies would provide the same (ScreenUsed.com does, but none of the other majors do).
Anyway, Propworx's COAs, addition of hologram stickers to the props themselves, and full online archive database is the current state of the art. I can't think of anything practical that's better.
I recently obtained patches from a SciFi series for my collection groupwise from differend sources like several well known prop stores and a propmaker of this series.
Then i sold some of the patches i had doubly in my collection. But as i had only COA's for groups of patches i added photocopies
of the pertinent COA's to proof the patches origin. I this case what can someone do? Not everbody understood why i only could send photocopies.
I usually include the original COA to the new buyer when I resell part of a lot, because it typically helps raise the final price and because if I part out a lot the item(s) I keep are usually ones I intend to keep permanently. Also, as the original buyer whose name is on them I figure my invoices, receipts, or other records of the original sales transaction together with color copies of the COA would most likely be adequate provenance for future buyers (or auctioneers/retailers) should I decide to sell the rest of the lot later. The original COAs themselves have little or no point or anything they'd add to a display once you've got hundreds of screenused props and costumes sitting around.
At least, the ones from companies start to feel superfluous; I've got a few personal notes from production members that I do display with their items.