Answer:
The detail that suggests that Darjeeling tea is among the best in the world is that companies falsely claim their tea is from Darjeeling.
Explanation:
Although the original poster did not provide the original passage mentioned in the question, it is most likely that the fact other companies claim their tea is Darjeeling is one of the indicators that Darjeeling tea is of a quality others want to imitate and lay claim to, Currently, the India government claims that about 70 percent of all tea sold as Darjeeling is not authentic. There are many who label their tea as Darjeeling but it actually doesn't come from the area. India sought a geographical indication mark from the EU so they could protect the product against those who are falsely claiming to be producers of Darjeeling tea.