Welcome to the physically based shading in Cycles, I hope you will find your new materials to be the secret weapon to stunningly realistic renderings!

As they are created with a different approach than standard and principled shaders, the interface is a bit different... But not more complex, quite the opposite in fact. Each material has its own IOR curve carefully reproducing light attenuation, so no input on your side is needed; depending on the material, you may alter its roughness, bump size and strength, its texture coordinate and/or its base colour

Materials included:

Titanium

Gold

Copper (also included in https://blendermarket.com/products/physically-correct-metal-materials)

Platinum

Silver

Velvet

HDRi from https://hdrihaven.com/ by Greg Zaal, licensed as CC0 (big thanks to him!)

Please note that this product includes only materials and render setup, 3d models and gem materials are not included