Scott Disick Buys GF Amelia Hamlin $57K Artwork for 20th Birthday

Scott Disick can't stop, won't stop spoiling his GF, Amelia Hamlin, for her 20th birthday ... 'cause it seems he saved the best gift for last.

Sources with direct knowledge of the deal tell TMZ ... Scott purchased a very pricy art piece Wednesday at the ArtLife Gallery Pop-Up in Miami's Design District. The item's a Saddle II, Paris 1976 vintage silver gelatin print by Helmut Newton.

We're told Scott dropped a cool $57k for the print and he completed the purchase using EthereumPay cryptocurrency. Fancy that! We're told the purchase had been in the works for a while ... 'cause Scott's the one who reached out to ArtLife about copping the piece.

As we reported ... the happy couple hit up the 305 to celebrate her bday last weekend. Dinner included a gold, shiny and MASSIVE 5-tier cake, and a diamond-encrusted cross necklace that nearly brought her to tears.