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The 25-year-old came through 64 minutes of the Scarlets' 18-13 victory against Munster on Saturday unscathed.
The centre has only just returned after recovering from a pectoral injury suffered in Wales' defeat by South Africa last November.
But after watching him in full flow, Jones - who won 47 caps for Wales - says he is ready for international rugby.
"Jon has shown he is fit," said former wing Jones.
"He showed in his first carry of the game that he hasn't lost any of that line-breaking ability
"I am sure he will give the Welsh camp a boost when he goes back in."
Davies has missed the opening three games of the RBS 6 Nations campaign against Italy, Ireland and France.
But Jones believes the week of training he put in with his club will stand him in good stead.
"Jon was very good and had a good week with the group, in terms of a leadership role," added Jones.
"He was very vocal and instrumental in us preparing well and I think it has been one of our best training weeks.
"I think his performance was pretty good, considering the length of time he has been out and the lack of rugby he has had."