The minimum size for prims in Second Life is 0.010M and although this may seem pretty tiny when making jewelry and other small accessories that this is still not small enough. So how do you get it smaller? There are 2 ways. 1. Nano Sculpties, these are sculpt maps that make small sculpties, and 2. Tiny Prims. Tiny Prims are made by a normal prim and then cut, hollowed and more. All prims can be made tiny by a few simple steps, but not all will look as the original prim did once sized down.

Cube:
Rez a Cube
Set the Cub size XYZ  as 0.10M
Change to Sphere

Change Dimple Begin .025 End .075
Change back to Cube
Path cut Beginning .625 End .875

Cylinder:

Rez a Cylinder
Set the Cylinder size XYZ  as 0.10M
Change to Sphere
Dimple .490 and .510
Change back to clinder
Taper X-1.0 Y-1.0

Stick:
Rez a Tube
Set the Tube size XYZ  as 0.10M
Hollow: 95.00
Profile Cut Begin: 0.500 End: 0.750

Spike
Rez a Sphere
Set the Sphere size XYZ  as 0.10M

Dimple Begin 0.950

For more informations on tiny prims and other expamples you can Torly Lindens video tutorial at http://www.youtube.com/watch?v=m6XqQM9hgB0 and visit Natalia's Creating Jewelery Part 3 at http://www.mermaiddiaries.com/2007/05/day-223-creating-jewelry-part-3.html