Note: In this explanation I speak only of beads, but despite it being unmentioned, hair clasps (such as the one we see Kíli wearing in movies) fall into same category with beads. Also, when not mentioned otherwise, beads (and clasps) are made of silver.
Edit: I forgot that FanFiction doesn't approve web links :D I hope the problem is now corrected, just delete the spaces in the link if you want to check the site.
Dwarves are very proud of their hair and beard, but while a dwarf who has lost their braids (or beard) is seen as having lost their honor, braids themselves hold no significant meaning to Dwarves. What are significant are the beads braids are secured with.
Childhood beads
Until a dwarf turns forty, he/she will tie his/her braids with simple silvery beads, which don't yet have family sigils. The only ornament in these "children's' beads" is small gems embedded in beads. These gems are always agate, be the child girl or boy, as this particular stone is believed to protect its carrier from harm.
"Teenage" beads
When a dwarf turns forty, (s)he can wear their family sigil in beads. The difference here is that a boy will get his own sigil, whereas a girl will wear her father's sigil until she marries, when she will start wearing her husband's sigil*. Though the beads are now made of silver, there'll still be agates in them to signify that the dwarf is not of age yet, and of course to protect this, let's say, "teenaged" dwarf.
*When of noble blood, a dwarrowdam can wear the sigil of her birth family even after she has been married. For example, Dís can wear beads that show she's a princess and a descendant of Durin, despite having been married (the fact that she's widow is irrelevant).
Adulthood beads
Having reached the age of seventy, a dwarf can start wearing beads with their family sigil and without agates. The first beads are usually a coming-of-age gift from the young dwarf's parents, and traditionally have only the family sigil engraved in them. A dwarf may also receive beads that mean they have achieved something noticeable, such as done great deeds in a war. These beads that signify one's status are not given out too easily, though. As for a bead that would show one's status as a lord or lady, such a thing does not exist. A dwarf's nobility is shown in their family sigil, so there's no need for a bead that would tell everyone that a dwarf is of noble blood.
With silver as standard base of all beads, beads with different engravings can easily be combined, and thus a handmade bead is a popular gift to give for one's loved ones. These beads have no meaning in shape of one's status, but they still have their personal meanings for the dwarf who's wearing them, these meanings not a tad less important than the meanings of those that show a dwarf's status.
Courting beads
Courting beads are the only beads which don't have silver as a standard base. The objective of this is that the courting bead would "pop out" from among all silvery beads, and thus signify that this certain dwarf is "off the market". The courting bead can of course be made of silver, but then it would lose its feature of being noticeable. Usually courting bead is made out of a gem, and the gem you use is a message of what you want for your courting partner. Here are two examples:
Tiger jasper is a stone of strong security and stability, as well as strongly protective stone. It gives one the courage to speak out and have personal independence.
Jade is a symbol of successful love, and the gem is also used to attract love. Jade can also be used to bring money into one's life, and it is also a strong stone of protection, guarding against accidents and misfortune. Jade also helps body in its self-healing process.
In the end, though, the chosen gem has also some kind of personal meaning, as many gems have somewhat same symbolic meanings. The only gem that is (by an unwritten rule) not used as base for a courting bead is agate, as it's so strongly present in children's beads.
(You find the meanings I have used from this website: crystal-cure gemstone-meanings . html)
The engravings in the courting bead symbolize those features of the courting partner which are dear to the dwarf who engraved the bead.
Hair decorations
Along with beads, female dwarves (of any age) usually have different kind of decorations in their hair, too. These decorations can be almost anything from ribbons to pearls, as long as they can be attached to one's hair. Most of the time this kind of jewelry does not have a meaning, the only exception being what is known as "widow's jewelry"; the overall coloring is black and the sole gem used is black onyx (for it can help to release sorrow and grief).