[BIGINJAPAN]

http://www.zerohedge.com/news/tungsten-f...y-district

Really the only way to guard against this other than carrying around a mini drill and bit is the ultra sound test. It is also very unlikely this is happening to anything smaller than a 10 oz bar. Just be diligent and be careful when buying. Perth mint is my place to go for the bigger sizes and I haven't heard or seen anything at this point to make me distrust them.

[Menace]

Tungsten filled gold bar will have different density. I would think you could just use Archimedes principle to verify, although the volumes of water displaces have to be sufficiently different to be readily measurable.

[BIGINJAPAN]

The difference isn't noticeable. That is why tungsten is used and not something like lead. The density is almost identical.

http://www.engineeringtoolbox.com/metal-...-d_50.html

[Alphabrew]

Another good reason to buy 1 ounce coins. You pay a hefty premium but there's no incentive to fill them with tungsten. I think I'll mint some tungsten coins and put Bernanke's face on them.