BB previously introduced Lucky Explorers for gems (Merchant\Black Market) I like it.
That would be good they would do the same with other event specialists too. If somebody missed the event or can't buy for event resources they have chance to buy for gems.
These specialist the following
- Intrepid explorer
- Experienced explorer
- Courageous explorer
- Consientious geologist
- Iron-Willed geologist
Or items that was in guild market.
For example Permanent Building Queue Slot. That would be good to increase the limit +1 and if you didn't bought for guild coin you have chance to buy for gem.