42 Verification of data and certificates concerning gems and gemstones, watches, art, and luxury items, and antiques, and sale and auction of gems and gemstones, watches, art, and luxury items, and antiques; Verification of data and certificates concerning gems and gemstones, watches, art, and luxury items, and antiques, and sale and auction of gems and gemstones, watches, art, and luxury items, and antiques using blockchain technology; Providing information concerning gems and gemstones, watches, art, and luxury items, and antiques, and sale and auction of gems and gemstones, watches, art, and luxury items, and antiques; Providing information concerning gems and gemstones, watches, art, and luxury items, and antiques, and sale and auction of gems and gemstones, watches, art, and luxury items, and antiques, all by means of web-based applications, mobile applications, and computer networks; Providing a web site featuring temporary use of non-downloadable software that enables users to list and participate in sale and auction of gems and gemstones, watches, art, and luxury items, and antiques; Providing a web site featuring temporary use of non-downloadable software that enables users to enter and view online and augmented reality galleries featuring gems and gemstones, watches, art, and luxury items, and antiques; Providing non-downloadable augmented reality software for converting 2D images into 3D images, and viewing images of gems and gemstones, watches, art, and luxury items and antiques; Providing a web site featuring temporary use of non-downloadable software for converting 2D images into 3D images, and viewing images of gems and gemstones, watches, art, and luxury items and antiques; Providing user authentication services using blockchain-based software technology for cryptocurrency transactions; Verification, issuance and validation of digital certificates; verification, issuance and validation of digital certificates for gems and gemstones, watches, art, and luxury items, and antiques, and sale and auction of gems and gemstones, watches, art, and luxury items, and antiques