Robert Pattinson spent £30,000 on Kristen Stewart's 23rd birthday present - a luxury, limited edition fountain pen.The 'Twilight Saga' actor splashed out on a limited edition Bentley fountain pen for his girlfriend to add to her collection and even had the writing tool engraved to commemorate her turning 23 on Tuesday (09.04.13).A source told the Daily Star newspaper: "Kristen has always collected pens, and has a variety of stylish ones. Rob decided to go big for her birthday this year and brought her a limited edition white gold Tibaldi Bentley Crewe fountain pen."He had her name specially engraved on it with the year and wording: 'From R'."There are only 40 of these pens in the world, so it's a real collector's item."The 26-year-old actor chose the gift because it had a British history, as it has been created in collaboration between car makers Bentley and Italian luxury pen designers Tibaldi.The source added: "The pens have a two-tone 18-carat yellow gold nib covered in rhodium and ruthenium."The barrel is identical to Bentley's dashboard used in their earliest car."The 'Bel Ami' actor also presented Kristen - who cheated on him last year with married director Rupert Sanders - with an antique bracelet and asked her to officially move back in with him.The source said: "They've, been taking it slowly, but Kristen has gradually won back his trust."Rob has taken a giant leap by officially suggesting they buy a love nest together."On her birthday, Kristen and Robert were seen at Hanson's album release party at Los Angeles Jane's House Lounge, along with friends Nikki Reed and Ashley Benson.An onlooker said: "Rob came in and sat down alone for about five minutes. And then Kristen came in with a security guard and sat down next to Rob. They were all hanging out in front of the other guests and looked like they were having a great time together."