This was pulled from a UC fan site, and Im not 100% sure that Luck works the same way on GC as it does UC. However, Ive be using these guidelines recently and been doing quit well during Rare and Uncommon times.
Things you need to know about luck:
You CANNOT use luck artifacts on other empires. You know how it says "The artifact makes a deep humming sound and disappears with a dark brownish glow."? It *sounds* cool, but after checking the recipient`s events, nothing shows up, and if it doesn`t show up in events, it didn`t happen. Period.
-Suertes do not stack on Suertes, and Afortunados do not stack on Afortunados. This means that if you use lots and lots of minor and major suertes on you, it`ll only take the effect of the last one that you just used.
-Suertes CAN stack on Afortunados, and vice versa. This means that If you use a Suerte on you and an Afortunado, you will get double the luck as opposed to just using one or the other.
-An Afortunado and a Suerte will yield the same results if they are used separately. Basically, a person that uses an Afortunado will get the same results as someone who uses a Suerte, as long as the time does not expire.
- Afortunados are governed by time, Suertes are governed by Turns. Afortunados last a certain amount of time (Minor ~10 minutes, Major ~30 minutes), whereas Suertes last a certain amount of turns (Minor ~20 turns, Major ~ 100 turns). The exact amounts are not certain, but this means that it may be impractical to use suertes when you are digging, but a good choice when you are using Regalos.