Is zakat obligatory on gold saved to buy more gold for marriage, knowing that it has not yet been sold and approximately a year has passed since its acquisition?

If the gold reaches the nisab (threshold), which is approximately 85 grams, the hawl (one lunar year) is calculated from the date you recovered it. Zakat becomes obligatory on it when one Hijri year has passed, as long as it remains in your possession. This is not among the exempted permissible jewelry, because you did not intend it for permissible use.