Some manufacturers still follow the old tradition by hand hammering singing bowls and in some cases, the results are pretty amazing. Other manufacturers produce singing bowls by pressing, casting and cutting on turning machines, but the work they do pales in comparison to the work of the alchemy masters of the past.
The alloys used today are quite different from those used traditionally. Centuries ago singing bowls were made out of bronze with traces of other metals that the main two ingredients, copper and tin (approx 80/20) were contaminated with. Today singing bowls are mainly made of brass, which is a combination of copper and zinc. When you look at certain antique singing bowls, you can see the level of mastery and care they were hammered with. Some antique bowls have such a smooth wall, it's hard to believe that they were hammered at all. I am taking full responsibility by saying that contemporary bowls are made with much less care. Nonetheless, sales are flowing anyway! A very small percentage of practitioners are familiar with the good quality of singing bowls. In many cases, fresh sound workers are not trained at all to listen to the fine nuances distinguishing the real masterpiece from a junk singing bowl. Instead, they were taught to put a bowl with a certain note next to a corresponding chakra. I am also familiar with many teaching “masters” who don't possess good quality instruments and still make many sales after they have done teaching the class.
The students (and teachers) don't know what they don't know until someone demonstrates a real jewel and points out the unveiling aesthetics of sound.
To make it even a better sale, modern singing bowls are crafted with various images of Tara or Buddha, lotus flowers and mandalas. I spoke to a woman once who took a very pricey sound healing workshop. Her teacher told her that a singing bowl will not bring any benefits if there isn’t a mandala or mantra written on it. “And you believed it!” - I said (there was no question mark at the end of my sentence).
So what is the main difference between the old and the new singing bowl? Usually, the old singing bowl will sound softer and sweeter than a new one. The energy it emits has a soul, versus the metallic (although pleasant) sound of the newer ones. It varies from one instrument to another and this opinion is certainly not applicable to each singing bowl. Generally speaking, when you get familiar with the acoustic features and go beyond the concept of sonic vibrations, you start to realize the subtle energy that sound is carrying. Most likely you will prefer to work with the antique bowl then. In terms of investment, antique bowls are growing in value because of the age and the fact that these instruments are vanishing from the market. If contemporary singing bowls are growing in value, it could happen because of raising the price of copper or the salesman's myths.