Spider Scrolls has all the info.
Here is a little tip from that page:
"In most cases, three spiders will be created from a successful combination; however, the amount is doubled if a gem of flawless quality is used instead of a standard gem."
So as a pickpocketing thief, use cash to get Gems which are Flawless then make Spiders, you can churn out 6 at a time.
Spider Scrolls has all the info.
Here is a little tip from that page:
"In most cases, three spiders will be created from a successful combination; however, the amount is doubled if a gem of flawless quality is used instead of a standard gem."
So as a pickpocketing thief, use cash to get Gems which are Flawless then make Spiders, you can churn out 6 at a time.