Digital X-ray technique
One can see the internal structure without damaging the beads. This test is done without complication up to Eight Mukhi, but higher Mukhi beads may not give 100% accurate results due to overlapping of the internal seeds.
CT scanning
CT scanning is another method for identifying Elaeocarpus sphaericus, but it is more expensive than an X-ray. It gives clear results than an X-ray.
Water Test
Any item, including Rudraksha, having Specific gravity greater than 1, are denser than water and will sink in it. Those with a Specific gravity less than 1 are less dense than water and will float on it.
Rudraksha will both float and sink in water, depending on how much moisture is trapped in the Bead. If the bead is dry due to dehydration and aging and does not have enough moisture, it will float on the water despite being original. Once you wear them, over time, as they absorb moisture and oil, they start sinking.
Due to the heavy demand for Rudraksha, farmers pluck the Rudraksha fruit from trees before maturity. This is more prominent in large-sized beads as farmers hope to get higher mukhi like 13-21 Mukhi, which they can sell at higher prices. Rudraksha Seeds tend to be lower in density if plucked before maturity. Hence these Rudraksha floats on water due to less density. However, they are genuine, provided they are not tempered by any other means. A ripen and matured Rudraksha usually sinks in water since it has a specific gravity higher than water.
Most of the Indonesian beads are small in size compared to beads from Nepal, have low density. This is true for even higher mukhi as well. So, though they float on water, they still are powerful, result-oriented, and bless their wearer.
Even a fake Rudraksha made out of wood and impregnated with lead will sink in water, thereby giving a false impression of a real Rudraksha.
Hence water test is not a reliable method to differentiate genuine and fake Rudraksha.
Coin Test
Rudraksha has electro-magnetic powers, so it will rotate if kept between copper coins. If in a seven mukhi Rudraksha 2 extra lines are carved even then it will rotate but will have the power of 7 mukhi and not of 9 mukhi.
Unnatural Cut
In fake beads made by carving extra lines, you will find unnatural cuts along with natural cuts. These unnatural cuts are mostly straight and do not have branches as in the natural face. Study each mukh/cut/face individually with a magnifying lens.
One should take extra precautions to buy 1 mukhi Kaju Rudraksha, Gauri Shankar, Trijuti and higher mukhi Rudraksha (14-21mukhi). They have more demand than supply and are faked in many cases by carving extra lines, gluing two or more Rudraksha together, or making from the fibre.