Hallmarking on Gold & Silver Jewelry

What is hallmarking:

Unless alloyed with a very small quantity of some other metal, both Gold and silver are too soft to withstand wear and tear while being adorned. It is very easy to carry out adulteration of an alloy into the precious metal without change in its color or touch and is difficult to detect without technical tests. Therefore hallmarking is the accurate determination and official recording of the proportionate content of precious metal in Gold and silver. Hallmarks are thus official marks used in many countries as a guarantee of the purity of fineness of gold jewelry (BIS).

Why hallmark using lasers:

Laser marking is an etching process; therefore it does not cause any bruising or distortion of the metal.

It is possible to mark both flat and curved surfaces.

Laser hallmarking does not require any physical contact with the item. A very precise fiber laser-engraving machine applies it.

The valuable items may be damaged or distorted if marked by the old punching methods.

The Finished article does not need to be refinished.

Lasers not only improve the clarity of the mark, it also allows items as small as rings or earrings to be marked.

Laser hallmarking is ideal for hollow or delicate articles where it would be otherwise very difficult to mark.

The deep laser marking is long lasting and retains excellent definition even after polishing.

Choice of laser machine for Hallmarking Hallmarking laser marker uses a very small beam diameter; even lesser than 30 microns and yet have very high peak power.

The laser has to hallmark on a very highly polished surface. Hence the chances of beam bouncing off are very high. So the hallmarking laser should block the returning beam to avoid damaging its own resonator.

A diode laser has less than 10,000 hours of diode life versus more than 100,000 hours life expectancy of fiber laser giving it an edge over diode lasers. Smaller lifespan of the diode laser beam will result in increase in the cost of ownership and thus adding overhead expenses.

Normally fiber lasers need two passes to etch gold. First one to frost the gold and second to engrave. This makes the marking less sharp. One Clean mark must be preferred for hallmarking gold and silver jewelry.

When buying a Fiber laser for hallmarking it must be kept in mind that it should do the hallmarking in ONE pass only and not TWO passes.

One must beware of the low quality laser markers due to the following facts Low quality Scanners: The laser marking from the quality compromised galvo scanners end up in loss of sharpness of design. The life of such scanners is not more than 2 years after which they get defected.

Cheap Diode systems: Many cheap diodes are available but they end up being demanding and worrisome due to many technical reasons. Many organizations like Rofin, Trumpf, laser walletc from Europe are very reliable in quality but have less than 10,000 hours of life. These are fine lasers due to wonderful opto electronics.

Ordinary fiber laser markers have the problem of not marking adequately on gold whereas they mark very well on steel or other less polished surfaces. They damage their own resonator cavity due to a compromise in design on protection.

Warranty: Most hallmarking laser manufacturers do not give 2 years warranty on complete lasers, below which is speculative for such expensive machine but Markolaser JL comes with logo2-5years Centres can only make profits if the turnaround is very high.