From ABlogToRead:

Let me tell you about the newest and (coolest) new method that a
luxury watch company is using technology to help prevent anyone making
replica, counterfeit or fake watches from the brand. I don't always
know why companies care so much about this, but it is true that as time
goes on, fake watches are getting better. In an ideal world, there will
be a simple and fool proof way to tell if a watch is authentic right
away, from looking at the watch itself. We are not there yet. While
this newest method (as applied to watches) is interesting, it still
needs improvement as you need the paper work that comes with the watch
to authenticate the timepiece. Doesn't that sort of defeat the purpose
as someone who is cunning enough is just going to match a questionable
watch with real paper work? Maybe Parmigiani will figure out how to
incorporate the system into the watches themselves.

So what Parmigiani
is doing is using technology from a company called Prooftag. The system
has many applications, and seems pretty well suited to the watch
industry. Prooftag technology is able to take a thin substrate and
create a series of bubbles in it. You know, like bubbles in Jello. The
idea is that each time the substrate dries/hardens the bubbles that
will form will be unique. Honestly it is very clever to use bubbles in
this manner. A "bubble fingerprint." There is a reader/camera that
captures the image in manner as to identify it each time using a
special portable device or visually. A small card is provided with the
Parmigiani watch warranty papers that includes the Prooftag bubble
formation tag and special code.

Below the bubbles is a code. You go online or use a mobile website on your mobile phone and enter the code at Prooftag's website.
After you enter the code the site shows you an image of the bubble
formation that is associated with the code. You can then authenticate
it in two ways. See if the image on the screen matches that on the card
you are holding using your own eyes. If it is hard to tell and the
images look close, you can used the special instrument that Prooftag
offers that will line up the position and size of the bubbles compared
to that which is in their system. Overall it is a really great system,
and Prooftag has a good website that covers all the little details.

Apparently Parmigiani started selling watches that had warranty
papers with Prooftag bubble patterns starting last June. The concept is
great, and of course it is cool. Part of the problem however is that
unless the Prooftag identifiers are directly on the watch itself, you
still have the possibility of "funny business." It would be possible to
incorporate the tags somewhere on the back of the watch or on the inner
parts of the lugs. Now that would be impressive use of the technology
and really a prevention of passing off fake watches as real ones.