Thanks guys, @Maul, you are right, talking with Maul adds the entry "Become a full member..." @gsmanners , I've done it before but never checked to see if all entries were checked for a successful quest, only now I've noticed that many optional and non optional entries are left unchecked although the quest ends fine, about your suggestion collecting all but one stone before talking to Vex, I'll do it this round. There is actually a solution to the entry "Become a full member in the thieves guild" added right after talking to maul. If after completing "Taking Care of Business" you talk to Mercer Frey, who gives you the follow up quest "Loud and Clear " and welcomes you to the guild as a member - NEVER talk to Vex right away , if you do, the line "Become a full member in the thieves guild" will never go away, you should first talk to the girl who gives you the full armor set (forgot her name), then the entry is cleared, you are a full member, then go and speak to Vex about the unusual stone. Thanks all of you guys