invented to keep out the cold
Alright. What does she actually want here? What would a good resolution look like?
Morgethai's eyes on this? Yes, that seems correct. No other source that competent will be nearly as trustworthy. That means she needs it held safely long enough for her to request archmage intervention. Gem contract deadline has passed, so she should be receiving a Sending (or some other contact method) soon. A week of holding should be sufficient. Any options for that better than the Bank?
...Nothing she can think of has any advantages besides obscurity. Might someone have a way to steal from this branch which was not previously worth triggering? It's possible. From the Absalom branch? ...anyone who can manage that and notices this would probably be able to steal it from any other storage area. The Abadarans are capable of not leaking the fact that they're storing something new and interesting, so any detection would come from their perhaps-foolish lack of security while bringing this into the area. That means... this probably opens no new vulnerabilities.
"We have observed no signs of intelligence or independent action. For the rest... Yanor, I think it your choice how much to disclose?" Silently agreeing that storing it in the bank is ideal, and that they're just haggling over the price. If Yanor has a strong preference she'll assume he has a reason, but if he doesn't, the default option is now the one she wants.