In both water and paint the buyers are testing the lead in the 1891 Victorian coin.
Queen Victoria was born in 1819 and ruled United Kingdom from 1837 – 1901. As one of the most notable British Monarchs, Queen Victoria's reign resulted in a number of popular and collectible gold and silver coins.
The 1891 Victorian penny is considered worth more than Bitcoin. On a gram for gram basis, the price paid by the anonymous buyer made it around 100 times more valuable than gold.
Hence, in order to check the lead, the buyers want to get both the water and the paint tested.
To learn more about Victorians here:
https://brainly.com/question/3728652
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