Why was Gustav lying about the source of the diamonds and what are 'conflict' diamonds? After a lot of searching, I found the answer. Conflict diamonds come from countries in the world where there is civil war. Rebel armies, which fight against the governments of the countries, mine diamonds and sell them illegally. They use the money to buy weapons, which allows the fighting and the bloodshed to continue. This has happened in many countries, including Sierra Leone, Angola and the Democratic Republic of the Congo. Conflict diamonds are estimated to account for only about four per cent of the world's production per year. This might not sound like a lot, but it is thought that in the last six years, an Angolan rebel group called UNITA has raised $3.7 billion from selling conflict diamonds. The proceeds from diamonds is thought to be the only source of funds for some of these rebel groups, so the rest of the world has decided not to buy any diamonds from these countries.

Stopping people buying conflict diamonds is not simple, as they can be smuggled out in to neighboring countries such as Liberia where they are sold as legitimate diamonds. How do people know this is happening? Geologists can estimate how many diamonds a region should have in its volcanoes and rivers and how much it will produce in a year. Some countries appear to be selling more diamonds than physically possible, so they must be getting them from somewhere else, such as smuggling them from countries where diamond selling is banned. The diamond companies are worried that if the public were to think that that there is a chance that the diamonds they are considering buying are funding wars where people are dying, they may not buy them, which would result in the collapse of the diamond market.

So how did James's colleagues know from the laboratory report that they were conflict diamonds? The lab test showed that the signatures of the diamonds were typical of conflict diamonds? There was something about the diamonds - some evidence within their structure that gave clues about the region of the world where they were mined.

Can we know where a diamond has come from?

Lets look at the evidence we have so far. We know that diamonds contain small amounts of other substances, known as impurities, which can give them color. Special optical techniques can be used to determine what the impurities are. These impurities give a possible start to tracing diamonds. For example, it is thought that Sierra Leone has a distinctive profile of sulfides (sulfur-containing molecules). Unfortunately, these tests have not been carried out routinely by all of the diamond producing countries of the world. To get this sort of information a lot of research would have to be done by testing diamonds from every mine. One of the major pitfalls of this type of identification is that all diamond is formed in the molten rock of the mantel. Rather like a pan of water being heated, the mantel has very slow convection currents that keep it flowing and mixed up. Due to these currents, the chemical content of the mantel is thought to be similar everywhere around the globe. It is therefore likely that, even though diamonds are mined at many different parts of the earth's surface, the impurities in them will be very similar. In fact it has been found that is virtually impossible to distinguish between rough diamonds from conflict zones and those mined legitimately in countries such as Botswana, the biggest rough diamond producer in the world.

So are there other methods of identification? Scientists have looked at uncut unpolished diamonds from different regions of the world and they have found that their size, shape and surface roughness can be a key to where they come from. However, when lots of diamonds are mixed together from a number of different sources it is still very difficult to separate them out in to their different regions, because the differences between them are too small. It becomes even harder once they are cut and polished, as all these original features are removed.

Rain may be the key to identifying the origins of rough diamonds. When it soaks in to the ground it comes into contact with the diamonds. It can leave hydrogen atoms or isotopes on the surface of the gems that are unique to the rain water in that region. These atoms or isotopes are held very strongly on the surface so are not easily removed.

All of these techniques seem straightforward, but they do not work all of the time, so at present, all countries that produce diamonds legally have signed an agreement that they will not buy conflict diamonds and that they will keep records of each diamond that comes out of every mine. Every stone is marked and cataloged through out its life and its documents (or 'certificate of origin') travel with it. Using techniques such as branding this should be possible, but wouldn't it be much easier if a technique could be developed like the one James's scientist had in the film. Well, maybe it has! In June 2002, a company reported that it had developed such a machine that can be used on rough and cut diamond. It is not yet in operation but hopefully will be soon. The manufacturers say that it is like a photocopying machine - put a rough diamond in to it and it identifies all its unique characteristics, its origin and its value, then forms a blueprint of the diamond and keeps it on record, then it brands the diamond. The cost of this machine is thought to be about $1 million - not very much if you compare it to the profits made every year by the diamond industry.

Can you think of any other part of the film you would like investigating? Let us know and we can have a try. Or why not try yourself?