Sharon Osbourne's a grandma now!

While Jack Osbourne is experiencing the new joys of fatherhood, his mother Sharon is getting used to being a first-time grandmother.

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"Today I witnessed my first grandchild being born, life changing experience," Sharon tweeted Tuesday. "She is an angel."

On Tuesday, Jack's rep confirmed to Us Weekly that he and his fiancee, Lisa Stelly, have welcomed their first child -- daughter Pearl -- into the world.

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Grandma Sharon, 59, gave a live Twitter chat Wednesday and spoke a little more on her feelings about the new addition to the Osbourne family.

The Talk host even volunteered to babysit! She wrote, "I will love babysitting b/c with all the wonderful things we're giving away on The Talk on CBS on Friday, I'll be prepared!"

Jack's sister, Kelly Osbourne, also took to her Twitter to react to the birth of her niece. "Thank you so much for your congratulations but they really should be going to Lisa Stelly and Jack Osbourne! I am one proud Auntie!"

Jack, 25, and Stelly's daughter Pearl weighed a healthy 8 lbs., 6 oz. at birth. The couple announced their engagement in September.


This article originally appeared on Sharon Osbourne: Granddaughter Pearl Is "an Angel"