I have experience designing labels both at the low-level ZPL code and with design software (e.g. BarTender). I believe the 2824 Plus printer supports the ZPL language, although I have never worked with that exact model, but it should mean that a text-based label template can be constructed to print on your 8000D jewelry label format. In previous projects I have designed large format labels with replaceable "token" fields that allow a merge program to replace tokens with data fields (similar in concept to a mail merge for printing mailing labels).
In terms of software, depending on your interest, I would propose using Excel itself to drive the printing via a VBA macro. You have already stated that you use Excel, the VBA coding environment is included. As ZPL is comprised of text commands, it is well within the capabilities of VBA to perform the merge.
If a separate application is required, I would build a .NET application as part of this bid (C# or VB depending on preference) that lets you select an Excel file, a template and a printer. The program could iterate through all of the exported data, apply the data fields to the template and generate a label for each row in the sheet.
As my approach would require a working label design in ZPL, I have structured the project with two milestones so that coding would not begin until the label itself has been proven.