please help to buy a LRL

[mehdi789]

hello everybody and thank you for helping me.
i am e mechanical engineer and live in iran.
here treasure gold finding is illegal and finder will be punished savagely with our government.
because of this i have to buy a LRL from out of my country and can't test a number of detector.
anyone can tell me which of brands has a gold detector that can find big pieces of gold in maximum 15 meters underground in good condition of soil and environment?
the price is not important for me.
please tell me brands that worked and test previously and showed good competence.

thank you for answering me and i will appreciate it.

with regard mehdi