Hi Elizabeth, That is a beautiful bracelet!
I doubt that any type of sealant will work to hold the brilliant
color. Pigments (the chemical colorants in dyes, paints, plastics,
etc.) are fugitive to different degrees. This means that over time
and especially with exposure to light and/or heat, the colors fade
and/or shift. Purples are usually the most fugitive.
If you look on a site like Windsor & Newton (good quality artist's
paints), they will have permanence tables for each of their types of
paint according to the colorant. Earth-based natural pigments (like
iron oxide, chromium oxide, etc.) are more permanent than dye-based
pigments (phthalocyanine, quinacridone, etc.). Companies like
Windsor & Newton work hard to make their paints as permanent as
An example of very fugitive, cheap dye would be found in children's
construction paper. Put it in the sun for a week, and there is a
Cloth fades, carpet fades, artwork fades, photos fade.
You might be able to research on the internet what kind of dyes are
usually used on commercial pearls, then check their permanence.
It's sad but true that dye colors don't last forever.
Still, it is a very beautiful bracelet that you created, and many of
the things in life that are valued most are not permanent.