A jeweler friend gives her a 10-carat diamond necklace because she s "dear to his heart"

By Dahvi Shira
Updated January 07, 2011 07:15 PM

If the threat of more jail time doesn’t keep Lindsay Lohan straight, maybe this will.

Looking happy and healthy, the recently rehabbed starlet, 24, showed off some heart-shaped bling around her neck in L.A. Friday morning – a sort of keep-up-the-good-work gift.

The actress’s pal Pascal Mouawad – the famous jewelry designer behind Nicole Richie‘s House of Harlowe line – gave the Mean Girls starlet the 10-carat diamond Rosette necklace, estimated to be worth $25,000.

“Lindsay is looking great, she has a positive attitude, and we are looking forward to an amazing 2011 spending a lot of time together,” Mouawad, 38, tells PEOPLE.

Even though Mouawad says Lohan is “really driven with her career right now,” a source close to the duo says, “The two have no plans to work together professionally.”

Adds the source, “Lindsay is dear to Pascal’s heart, and he thinks she is headed down the right path. He wants to keep her going in that positive direction.”