ST. PETERSBURG, May 16. /ITAR-TASS/. Pieces of art are being marked for identification by a new pen and spray-mist proving themselves under tests at the State Hermitage Museum in Russia's northern capital, St. Petersburg.

Russian-made technology is being used to mark pieces of art leaving the famous museum's walls for temporary loan to other exhibitions, and to confirm authenticity of the treasures on their return.

The processes will be put to work later on the three million exhibits in the Hermitage collection, Vladimir Kuzmin, associate at a Russian Defense Ministry research institute, told ITAR-TASS.

Military specialists and a private Russian manufacturer have developed the marking process, working its magic via a trace visible under ultraviolet light. Museum staff will use this new technology for "friend-or-foe" recognition and for a new cutting-edge catalogue.

The system could spread to other Russian museums and has applications for the military, police and customs service, said Kuzmin.

For precious items that cannot be touched, the scientists have produced a unique chemical mist impossible to replicate and applied in a spray. Traces have a lifespan of no less than 50 years. The concentration is harmless for paintings, porcelain, glass and ceramics, the expert says. Technology is also being developed for metal objects such as coins, difficult to mark.

Marking detectors require no laboratory conditions or special skills, reading the coded information according to the "friend-or-foe" principle. When the device recognizes the object, it makes a sound signal and a green light comes on. A red light means the object is unmarked, or has an alien mark.

Marking can be read without disturbing an item and removing it from its location. The device will identify even burnt objects as the mark persists at a temperature of 2,000°C.

Protection comes relatively cheap from the developers. One mark costs 30 rubles ($0.86). Detecting devices cost between 50,000 rubles and 150,000 rubles (about $1,400-$4,300) depending on size.