Garuda Trading, in Cornwall, has these beads from Wu Tai Shan.
In Lieutenant-Colonel Laurence Austine Waddell's 1895 book The Buddhism of Tibet, or Lamaism, he makes mention of the manufacture of prayer beads at Wu Tai Shan, in China, for sale to the Tibetan market. He writes, "These beads are manufactured wholesale by machinery at the temple... ."
Indeed, it has been ever thus. The beads are made in something called a "bead mill." The material is drilled, cut into cubes, the corners are roughed off, and then these blanks are placed in circular mills which gradually machine them to size. They then put them in polishing drums, not unlike the polishing drums used to make Tibetan medicine. Even today, if you go to Wu Tai Shan (looking for Manjushri), you will pass by thousands of prayer beads for sale, made from every substance under the sun.
Lt. Col. Waddell's book, in 1895, was the first Western resource on the topic
So, like everything else, prayer beads are a fun subject with which to occupy your attention from time to time, and they have spawned their own body of myth and lore that is diverting to consider. The Dalai Lama's official website used to have a nice article on the subject, but I see they have taken it down in favor of more political content.
Recently, in another medium, a friend of mine noted that lapis-lazuli beads are used for the Medicine Buddha mantra, so this naturally sparked some interest in which material goes with which mantras.
I cannot pretend to any authority in this matter, so I will just pass along what I have heard. I will leave it to you to conduct your own inquiries.
I have heard that red sandalwood is favored for Hayagriva. Coral is also used for Hayagriva, as it is for Padmasambhava, and by some people for Vajrayogini, Red Tara, Kurukulle and so forth. Actually, red carnelians are the best for Kurukulle, but you don't often see these done nicely. The coral sets are very expensive: the good ones start at around $2,500 and go up from there. I think $3,000 is the average going price these days. I know an Indian coral dealer in Southern California, and I asked her if these prices were legitimate. She said that the coral fancied by the Tibetans is inferior to other sorts which are less expensive, but since fashion is fashion, the prices are reasonable.
For Manjushri, and certain of the deities associated with wealth, one sees beads of amber, hessonite, which is a kind of honey-colored garnet, topaz, and tiger's eye. It is widely reported that the Dalai Lama uses a tiger's eye mala, and indeed he has one. Actually, he has many different malas. The last time I saw him (2009), he had a simple bodhi seed mala. In any event, tiger's eye is just a chatoyant chalcedony, and the very best kind is a sort of blue and gold. The common ones are brown. The reddish ones are heat treated.
Tarthang Rinpoche's mala is made of goldstone. He acquired it in India, just before he came to America. Goldstone is actually octahedral crystals of copper dispersed in glass, using a process invented in the seventeenth century, in Venice.
For Tara, many people fancy turquoise, malachite, or even jade. For White Tara, you can choose pearls, which are also sometimes suitable for Chenrezig. Some people prefer white conch for Chenrezig. However, Chenrezig's thoroughly well-established mala is always of crystal. The lead crystal ones are usually inexpensive. The rock crystal ones can be very expensive. For the Medicine Buddha, there is lapis, as we have mentioned, but there is also aquamarine (blue beryl), and blue quartz (dumortierite quartz).
In Waddell's book, he states, "There is no rosary formed of finger-bones, as has been sometimes stated." Actually, there are. The fingers of great Yamantaka practitioners were sometimes made into disc-like beads. These are so rare as to be almost non-existent. You also find them of skull bone, and so forth. Naturally, these are associated with wrathful deities. You often find rudraksha used for this purpose as well. Sometimes, snake spines are used for particular rituals.
Lotus seeds are good for White Mahakala, as are bodhi seeds or even six-lobed rudraksha. You can also use ivory, although a good quality, pre-ban ivory mala will cost in the range of $500 these days.
There is an enormous body of superstition associated with malas, and you can get some of the flavor of this by clicking here. Sort of a "step on a crack and you'll break Mother's back" level of superstition. However, the properties and powers of the various minerals and materials are not superstition; rather, these are rooted in Vedic expression, thousands of years old, codifying the wisdom of highly enlightened beings.
Many Tibetan malas have counters of silver, or even gold. These tend to get in the way, so usually you only see lay people use these.
In most of the prisons in Tibet, malas are not allowed, so the prisoners make them of knotted bits of string. If these are found, punishment often ensues. Therefore, a method of using the fingers is preferred. You visualize each finger as being divided into four sections. Starting with your right thumb, you count across both hands and back again. This gives you a count of eighty. Next, you count across both hands and back, but this time only count one for each finger, not four. This brings you up to one hundred.
This is very, very "handy" to know, if you are on a three-year retreat and the mala breaks.