The short answer is yes. However, we should clarify that answer.
Typically, Discipleship Travel LLC does not make a visit to a diamond factory a compulsory stop for the whole group. Instead, the tour guide will inquire as to who in the group is interested in visiting a diamond factory. If anyone is interested, the guide will make arrangements for a visit one evening after the tour day is complete
There is no obligation to visit, or to buy anything if you do visit. Some people like to visit just to see what is available. Others have specific interests in buying a gemstone in Israel. Of course, the choice is yours.