According to law it's permissible to own a metal detector but it would be legally contrued to be offensive and against privacy law if you use it to poke in the space between two legs of another person no matter what you want to detect.
- They are legal.
- There is no license required.
- Customs can excise a 7% tax on imported metal detectors, although they may not even notice it.
Most of the Singapore public have never seen or even heard of a metal detector for personal hobby use. They will think you are looking for mines. I get puzzled looks all the time, and inquisitive on-lookers. Most are just curious, and a few ask where I got such a neat toy. Many are also dumfounded as to why I would spend the time searching for metal on the beach. They have no concept of "finders keepers" and believe I must have some official reason to be doing what appears to be "work"! The fact that many people ask me "Why are you looking for gold rings" gives you the best insight into Singaporean culture.
So while the Police pay no attention to me, and I am not breaking any laws, there are other laws that apply to this hobby that you must respect in order to stay out of jail:
1. You cannot deface any public property, such as parks. Vandelism is a serious crime in Singapore and treated harshly (think caning). Thus digging in a public park is not legal. On private land, you must get permission from the land owner, and this is not usually given due to the suspicians and ignorance they have towards the hobby. With that said, a public beach is the perfect spot to metal detect in Singapore. Digging in the sand is legal of course - but please fill in the holes.
2. You must not disturb the public. Thus headphones are a must, and you should not dig around people laying on the beach, or walking along the beach.
3. Here's the hard part: There is a Singapore law that states if you find a valuable item, such as a ring, you must make an attempt to find the owner if possible. It is the responsibility of the finder to show an attemopt to locate the owner.
That said, if here are no markings that would make the jewelry identifiable, then this may not be possible. It's not an easy law to enforce, or to obey. However, if you find a ring next to a person on the beach, and they see it, they may claim they just lost it and the law will be on their side (I have never experienced this). I would keep all found jewelry hidden until after you leave the beach. That way, you can inspect it in private, and if there is a name or other identifying mark you can choose if you wish to make the effort to locate the owner.
Bottom line - if you are caught with found jewelry and have made no effort to find the owner you are then technicaly guilty of the crime of "Misappropriation of Personal Property": with a possible jail term of 2 years. This is not a law that is too difficult to enforce, and the Singapore police I work with have never seen it brought up. They suspect that they would need to have a case where the owner of the said jewelry could show that not only the jewelry was theirs, but also that you KNEW it was theirs and kept it anyway. Only then I believe the police would bring a case against you, as there is no such thing as "Finders Keepers, Loosers weepers". If an object can be traced to an individual, they have the right to get it back, even if they left it on the beach a year ago!