Is the official exchange rate of the dollar or the parallel market rate used when determining the Sharia threshold (nisab) for Zakat, especially given the significant difference between the two rates?

It must be noted that the zakat threshold (nisab) is equivalent to 595 grams of silver, or approximately 85 grams of gold. The lower of the two is considered, because it is more beneficial for the poor and absolves the giver (muzakki) of their obligation more completely. So, if you own an amount equivalent to the nisab of silver, zakat becomes obligatory upon you, and there is no need to consider gold and its fluctuating prices.