Diamantes means 'diamonds'. While it might seem like a straightforward word, its inclusion in this song is particularly enticing because it represents a grand gesture of love and commitment.
In the lyrics, the singer expresses a deep, unwavering love and wants to buy a 'collar de diamantes' (diamond necklace) to publicly declare his affection. This word elevates the sentiment from a simple gift to a symbol of enduring, precious love, making it memorable and intriguing for a learner.
In "El Regalo", Spanish-French flamenco singer Mayel Jimenez is completely overwhelmed because his crush is finally talking. She is going around telling everyone she genuinely loves him ("Tú vas diciendo a la gente / Que me amas de verdad" [You go around telling people / That you truly love me]), and he admits he is literally dying of joy knowing it is not a lie ("yo muero de alegría / Al saber que es verdad" [I die of joy / Knowing that it is true]). So, what does he plan to do in return? Put on a massive public display, of course.
His immediate plan is to buy her a lavish gift so everyone can witness his devotion: "Te compraré un collar de diamantes" (I will buy you a diamond necklace). Notice how he sings "Pa' que lo puedas llevar" (So that you can wear it). That little word "pa'" is everyday spoken Spanish shorthand for para (so that / in order to), which you will hear constantly on the street and in flamenco tracks. His declared goal is not shy at all; he wants the whole neighborhood to see this sparkling necklace so they know "yo también sé amar" (I also know how to love). It is loud, dramatic, and shamelessly proud of falling deeper in love with every passing day.