We are selling a product internationally through our e-commerce based in Hong Kong and were wondering if our Hong Kong trademarks have any legal power in other jurisdictions.
If not, do we really have to register our trademarks in every (100+) countries where we ship our product ?
You have some good pointers by jimg already; see his links in the previous discussion on this site.
Just to be clear, your Hong Kong trademarks protect you only in the jurisdiction they're registered in. Given Hong Kong's unique recent history, I do not know if that's the "Hong Kong Special Administrative Region of the People's Republic of China" area, or all of the People's Republic of China.
If you where a big multinational company with lots of money, then you would register your trademarks in all semi-industrialized countries on the planet. The cost of registering a trademark globally is nothing compared to the potential problems it can avert.
If you're a cash-strapped startup, then it's harder. What you should do is a good question, one that I will leave to you. :-) One approach could be to register in your home country plus USA, since USA is a big part of the world economy and cheap to register in. Another approach could be home-country + USA + EU; that would cover much of the 'interesting' worldwide market, and still be manageable...
If memory serves me, then registration via the web interface is ~350 USD for USA, and ~900 EUR for EU. Note that in most cases this is non-refundable, i.e. if you don't get the trademark because it infringes on someone else, then you don't get the handling fee back.
You'd need to trademark in China as well (if you're shipping there). Enforcement may be iffy, but better plant the flag before someone else does.
An amusing aside, I have a pair of "Playboy" leather shoes because of lax TM enforcement in China. Starbucks did win a case though...
Two territories worth covering are Europe and the US.
For Europe, you can file a trademark request that will cover all EEC countries. It's cheaper and easier than filing one trademark for each country.
You should also consider subscribing to one of those "trademark watch" services that the IP service companies offer. That will ensure that you have someone looking at trademark submissions across the world and notify you if someone is trying to register a similar trademark. You can then act accordingly for each territory.
Hope this helps