I'm aware that Buddhist monastic communities often wear robes that distinguish them and visibly mark them out as Buddhists. Do lay Buddhist ever do the same thing? Is there any jewellery or clothing that lay Buddhists wear to mark them out as Buddhists - a visible marker of their religion. This is obviously common in other religions e.g. crucifixes for Christians - but do Buddhists of any tradition have an equivalent?
I'm in the US, with <1% self identified Buddhists in most counties. So there isn't a lot of established customs as there are abroad, where wearing say a white band in Theravada countries, or a pilgrims hat in Japan (worn by hikers as they hike from temple to temple).
I organized a Buddhist book club and generally don't use a table tent, I forget them and lose them. So the American thing to do for group identity is to get a T-Shirt.
I'm thinking of one like this: http://www.spreadshirt.com/gautama-buddha-fade-t-shirts-C3376A16488554#/detail/16488554T175A135PC1002313903PA296
While I believe your question was intended for everyday wear in Vietnam and only in the temples most lay practitioners wear a blue/grey uniform a bit similar to the monastic's robes. A practice followed in Vietnamese temples around the world.
See an example: http://afamily.vn/doi-song/le-vu-lan-chu-hieu-tron-day-20120827125422575.chn (Hungry Ghost Festival)
Nam Mô A Di Đà Phật.
Lay buddhists in their everyday life are not prescribed any distinguishing clothing etc. Buddha laid total emphasis on practice and this can be inferred from many stories of his lifetime. Though, when you go on a meditation retreat, as said by @Robin111, it is suggested that you wear clothing which fully covers your body and white coloured clothing is preferred. This is due to practical reasons and to aid yourself in the practice. But in day to day life, there is no prescription of any type of clothing or any other symbolism