How is the weight of a golden wristwatch, with its movement made of iron and plastic and its outer casing made of gold, estimated?

It is forbidden for a man to wear a watch containing gold. Zakat (definition) is obligatory on this gold if it reaches the nisab (definition). However, if the watch belongs to a woman, it is permissible for her, and the majority of scholars hold that Zakat is not obligatory on it, though it is more cautious to pay it. The method of Zakat is to estimate the weight of the gold in the watch and to pay a quarter of a tenth (2.5%) of its value, either by removing the gold if possible without damage, or by estimating its value if removal is not possible.