The following is a chart by Konrag detailing the types of stats unlocked

REFINEMENT JEWELS

A. Rule: Applying refinement jewels to your equipment grants you a chance to refine it by one level. Equipment starts at a refinement of +0, and can be refined to a maximum of +6 Star Trek Credits.

In addition to increasing your refinement level, refinement jewels have a chance of decreasing your level by one, upon failure.

Keep in mind that in order to refine a piece of equipment, you need to use the type of refinement jewel that corresponds to the equipment type and level.

The benefits that you obtain by refining your equipment will depend on the equipment itself, but in general you gain an increase to its current stats, in addition to unlocking hidden stats such as +crit chance, etc. The following is a chart by Konrag detailing the types of stats unlocked when refining armor:

This will double your maximum dynamic durability and grant you a 20% bonus for as long as your dynamic durability stays above 100. For example, a piece of equipment with a 100/100 durability rating will receive a 200/100 rating after repairing with a golden repair hammer.

However, once the dynamic durability drops below 100, through taking/dealing damage, you lose the bonus, and repairing the equipment via the vendor will only bring it back up to its static durability rating, which never changes.