The Glee star, 26, posted a close-up of her gold "Finn" necklace that her character Rachel Berry wears, alongside the caption, "Today... ❤."
The dainty item is modelled on the "Cory" necklace Lea often wears, keeping her late boyfriend close to her heart.
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Lea tweeted the picture from the set of Glee, while the all singing, all dancing cast were filming the special tribute episode that will be aired on 10 October in memory of Cory.
The talented actress will not be appearing until the final act of the episode, according to E! Online, when she will deliver a no doubt powerful performance. The episode will start off with the news that Finn has died, and follow through with the characters remembering and honouring him.
"Just read Cory Monteith memorial episode," tweeted Jane Lynch, who plays sports coach Sue Sylvester in the show, earlier this week. "Most beautiful thing. Thank you, @MrRPMurphy @BFalchuk Ian Brennan."
The cast of Glee have been working hard to support and comfort each other, and Lea is said to be doing an "amazing" job at holding her co-stars together.
"Lea has been amazing," a source told HollywoodLife. "She is definitely very sad, but has gotten so much better and has really been strong.
"The whole crew and cast are now a family and Lea is leading us all back to a normal set life. Cory was a cool guy and will be missed."
The show's leading lady has been letting fans into her Glee world and thanking them for their love and support following Cory's death from a heroin and alcohol overdose in mid-July.
Lea has kept fans updated on Twitter by posting photos from the set. A recent snapshot showed the star and her make-up and wardrobe team posing and having a laugh together, alongside the caption, "Beautiful shoot w/ my glam family... I love them so much! @EsteeStanley @marktownsend1 & @melaniemakeup ❤."