How is the zakat on used gold jewelry to be assessed: is it based on the price of used gold or new gold? And is zakat now obligatory on money that was saved in the 1990s for a specific purpose, upon which a full year has passed, and zakat was not paid due to ignorance, along with ignorance of the amount and the nisab?

Jewelry intended for adornment is not subject to zakat, according to the majority of scholars, though paying it is more cautious. As for saved money, there is no zakat on it if there is doubt about it reaching the nisab (85 grams of gold or 595 grams of silver). However, if it has reached the nisab, then zakat becomes obligatory on it for all past years, and it is not waived due to the passage of time or ignorance.