You are able to dye your own real or fake (not as porous as the real thing) pearls with this recipe. You could even try other dyeable items too.
It truly is easy. You just have to remember you always first do a colour test as you don't want to be disappointed. It's like when you dye or streak your hair; the hairdresser or yourself should always test a swatch first before you do the whole batch. Also keep in mind, when you dye anything it may get lighter gradually because of sunlight. I recommend you dye your MOP or whatever you choose to colour, dry it and leave it out in the sunlight overnight and see if this is the result you want.
You could choose to dye the pearls individually in a dish or on its strand. If you decide to dye the pearls on the strand you will notice that the dye will be more noticeable to the edges.
When using a store brand like Rit dye following the manufactures instructions to a point is important. The dye must be well mixed otherwise your pearls may end up having some spots. I suggest using a sieve of some sort to get all the reminants of the dye out prior to dying your beauties. You may have to adjust a bit to your own taste of the colour desired in the concentration of dye used; how much water did you put in; was the water cold or warm and how long did you leave it in the dye. If you love the results and you want to dye some more in the future consider writing down the porportions of all that was used and keeping it in a safe place.
You could make your own dye if you so wish. Please note that it will almost be impossible to make the dye twice. You must still do a colour test as the store bought dye. Place your pearls in the dye boiling waters and then let it simmer (pearls must be covered at all times) or when the water is cooling down in the pot. A double boiler is totatlly recommended as you don't want your pearls to lose its hardness or being suseptible in being fragile. Allow your pearls to sit in the water until you have achieved the colour wanted. Once when you have achieved the colour desired, you rinse the pearls with distilled water or, if you must, under the water tap until the dye is removed. After you rinse the pearls place them on an absorbent paper towels or hang them up to dry. If you ever boiled and coloured eggs for Easter you know what I'm talking about. If you haven't done such a thing, I know you are missing out on a lot of fun especially with kids.
Now you are asking what do I use to make your own dye. Try onion peel, flowers, herbal teas, spices, canned or fresh vegetables. If you add vinegar to the dye it will deepen the colour (approx. 1 tsp.).
Have fun dying your pearls or what ever you choose to dye.