Ok first off i know that there are guides for this on the site, but they are crappy.
Im tying to upgrade my pants to plus 15. I have plenty of stones including white ones but im unsure on how to go about this, i obviously dont want my armor to break.

1. What is the max limit for armor using regular upgrade stones before it will have a chance of breaking?

2. What are the purpose of White stones and how and when should i use them?

3. When should i use the purple armor upgrade stones?

1. i don't think there is a max.
2. white stones are their for an added boost?
3. you can use them instead of blue and red?

that is not true
1 for armour go to +3 and then you use a green stone for upgrading
2 white stones is for not breaking your item. if you have one use it for upgrading your item wil not break only failed
3 you dont use purple but green stones for armour and like i said in 1 use a green stone after your armour is +3 and for a sub weapon ore gloves you use a purple stone after +5. this way you wil not brake your item

1. max upgrade +15, safety is +4 armor, +6 weapon/sub.
2. white stone to eliminate from break. and u must use 1 upgrade stone (normal or pure) again,
ex: EQ + white + normal/pure stone.
that stone will work after u got at safety in upgraded. +4 armor, +6 weapon/sub. than
choose 3 cards to get success card.
if u got fail card (ur eq safe only stone will gone), if u got broken card (ur eq safe but ur +
upgrade will down with range
2 - 6 points). example : jacket +10, if u got broken, ur + will down to 2 - 6 points.
3. green stone, u can use it from +0. (that pure has change to up +1 till +3 points).

to get the trick, isoox96 was tell u. up ur armor to +3 with blue stone, then up again with green stone. so u have change to get +6 for ur armor. if u got only +1 (to be +4) u can downgrade it with green black stone to +3, then up again with green.
it same when u will up ur wep/sub, but u must up to +5 first, then use purple stone.