A pearl is a hard object produced within the soft tissue (specifically the mantle) of a living shelled mollusk. Just like the shell of a mollusk, a pearl is made up of calcium carbonate in minute crystalline form, which has been deposited in concentric layers. The ideal pearl is perfectly round and smooth, but many other shapes of pearls (baroque pearls) occur. The finest quality natural pearls have been highly valued as gemstones and objects of beauty for many centuries, and because of this, the word pearl has become a metaphor for something very rare, fine, admirable, and valuable.

The most valuable pearls occur spontaneously in the wild, but they are extremely rare. These wild pearls are referred to as natural pearls. Cultured or farmed pearls from pearl oysters and freshwater mussels make up the majority of those that are currently sold. Imitation pearls are also widely sold in inexpensive jewelry, but the quality of their iridescence is usually very poor, and generally speaking, artificial pearls are easily distinguished from genuine pearls. Pearls have been harvested and cultivated primarily for use in jewelry, but in the past they were also stitched onto lavish clothing. Pearls have also been crushed and used in cosmetics, medicines, and in paint formulations.

Stefani Joanne Angelina Germanotta (/ˈstɛfəniː dʒʌrməˈnɑːtə/ STE-fə-nee jurr-mə-NAH-tə; born March 28, 1986), known by her stage name Lady Gaga, is an American singer and songwriter. Born and raised in New York City, she primarily studied at the Convent of the Sacred Heart and briefly attended New York University's Tisch School of the Arts before withdrawing to focus on her musical career. She began performing in the rock music scene of Manhattan's Lower East Side, and was signed with Streamline Records by the end of 2007. During her employment as a songwriter for the record company, her vocal abilities captured the attention of recording artist Akon, who signed her to his label Kon Live Distribution.

Lady Gaga came to prominence as a recording artist following the release of her debut album The Fame (2008), which was a critical and commercial success that topped charts around the world and included the international number-one singles "Just Dance" and "Poker Face". After embarking on the The Fame Ball Tour, she followed the album with The Fame Monster (2009), which spawned the worldwide hit singles "Bad Romance", "Telephone" and "Alejandro". The album's success allowed her to embark on the eighteen-month long Monster Ball Tour, which later became one of the highest-grossing concert tours of all time. Her most recent album Born This Way (2011) topped the charts of most major markets and generated more international chart-topping singles, including "Born This Way", "Judas" and "The Edge of Glory". Besides her musical career, she involves herself with humanitarian causes and LGBT activism.

Joshua Winslow "Josh" Groban (born February 27, 1981) is an American singer, songwriter, musician, actor, and record producer. His first four solo albums have been certified multi-platinum, and in 2007, he was charted as the number-one best selling artist in the United States with over 21 million records in that country. To date, he has sold over 24 million albums worldwide, and is the top selling classical artist of the 2000s in the US, according to Nielsen SoundScan.

Groban originally studied acting, but as his voice changed, it developed into a "significant instrument". Groban attended the Los Angeles High School for the Arts, a free public school where students received a conservatory-style education. His life changed when his vocal coach, Seth Riggs, submitted a tape of Josh singing "All I Ask of You", from The Phantom of the Opera, to Riggs' friend, producer, composer and arranger David Foster. Foster called him to stand in for an ailing Andrea Bocelli to rehearse a duet, "The Prayer," with Celine Dion at the rehearsal for the Grammy Awards in 1998.Rosie O'Donnell immediately invited him to appear on her talk show. Foster asked him to sing at the California Governor's Gray Davis' 1999 inauguration. He was cast on Ally McBeal by the show's creator, David E. Kelley, performing "You're Still You" for the 2001 season finale.