Saracens' latest injury setback comes shortly after first-choice No9 Neil de Kock was sidelined for a similar period with a broken arm.
"It's a blow for Moses and after going for such a long time without any injuries to our halfbacks, we now lose two in the space of a week," said Sarries director of rugby Jones.
"Mickey Wilson did very well when he came on against Viadana and he will be carrying the torch for us this weekend against Mont de Marsan in the final European pool game."
Despite capturing the services of former All Black Justin Marshall last week, Jones admits Rauluni's injury means he will now be looking to bring another scrum-half into the squad at the earliest opportunity.
"Signing Justin on a short-term contract is now looking even more important but we can't go through the next few months with only two scrum halves in the squad so we will be looking to recruit another player in that position and we'll be doing that over the next few weeks."