Gogling came up with something you may want to read:
Originally Posted by http://www.allianz.co.uk/media/press_story.asp?Recno=1279
Smartwater - An Outstanding Instrument
SmartWater, a forensic security coding product, is being provided to all new and renewing policyholders of Allianz Musical Insurance as of 1 August 2007 – a product used by police forces across the UK as part of a concerted strategy to deter crime.
This is the first time a tangible product has been incorporated within an insurance policy – a product that links coded possessions directly with their owners, and one which has been proven to reduce burglary by up to 83 per cent*.
Nick Grazier, musical insurance manager for Allianz Insurance said: “SmartWater has been likened to DNA profiling and is essentially an invisible liquid barcode, only revealed through ultra-violet light. We are taking a proactive measure to prevent our policyholders from suffering the emotional strain caused by theft or loss of a musical instrument.
“Each SmartWater system contains a unique forensic code which is simply dabbed into the nooks and crannies of the musical instrument. With only one billionth of a part required to provide irrefutable evidence to secure convictions, SmartWater is proving to be a criminal’s worst nightmare
SmartWater chief executive, Phil Cleary, added: “By protecting musical instruments with SmartWater, Allianz Musical Insurance’s policyholders are five times less likely to suffer criminal victimisation. Thieves are well aware that SmartWater has the power to convict them, and this will often deter them to the point of abandoning their plans altogether.”
*Perpetuity Research (University of Leicester) 2004
So it's kind of like "DataDot" that they use for some cars.