Just curious what other people’s luck has been when upgrading jewelry. I’ve only tried upgrading from lv1 -> lv2.
I’ve always worn max charisma + luck items and used a bonfire. No potion of luck though.
1/16 is my upgrading success so far lv1->lv2
Assuming the success rate is a shitty 1/5, (16C1)(1/5)(4/5)^15 is the relevant numbers for your situation, which happens about 11.26% of the time. Comparatively speaking, getting 2 or 3 successes happens about 45.74% of the time.
As an aside, to get a jewel from level 1 to 5 in 8 tries only happens about 2.29% of the time under a 1/5 success rate.
Quick tip… it’s kind of a waste to upgrade a level 1 jewel, since level 2 jewels drop from Pandora’s minigame. Something to think about.
Level 2 jewels blow up for more dust than level 1 jewels, so it’s not particularly wasteful even if you get a duplicate level 2 jewel from pandora later. If you’re not ‘buying’ passes, it takes a while to get your level 2 jewel of choice. So it helps, in that case, to upgrade and use it while you’re waiting to become a lucky son of a bitch.
I’ve only gotten 1 lv2 Jewel from Pandora’s Bag and that includes the Free 3 attempts/day since start and probably 45-50 Pandora Passes from donating a couple times since it started. I figured I would attempt to upgrade my Jewels to lv2 now rather then later since it may take me to Christmas to get a few of the the lv2 Jewels that I even want to use regularly from Pandora’s Bag for free 
I also thought that since the lv2 Jewels are a probability from Pandora’s Bag it would be easier to upgrade them from 1->2, but I’m beginning to think that is not the case.
I was trying to get a Opal level 2 before start update.
After 4 days, decided to upgrade lvl 1 - 2 - 0/12 so far.
Got a level 2 Sapphire and tryed to over it.
I made a level 4 sapphire.
Lvl 2-3 - 1/1
Lvl 3-4 - 1/1
Bonfire and 4 mia’s only.
You currently have the only level 4 on the server FakeAgent
Seems like 1 person got extremely lucky making a lv4 while most others can’t even upgrade to a level 2… 
Well… im still trying to make a Opal level 2.