Nations with the largest nuclear arsenals.

The history of the world's most precious gems is always full of surprises and fascination, often intertwined with that of kings, emperors and wealthy businessmen. Even in our time, they have kept intact all their beauty, rarity and pricelessness that always leave one breathless.

No one knows when man first discovered gemstones, but from the earliest civilizations they have meant power and wealth.

Some people believe that wearing them can bring success in business, good luck and keep bad luck away.

The twentieth edition of the QS World University Ranking has been released, which reports on the best universities around the world.

The ranking takes into account 1,500 institutions in 104 locations and is the only one of its kind to emphasise the value of employability and sustainability. This year, three parameters have been added to the criteria for evaluating universities: sustainability, employment results and international research network.

Let us therefore discover which are the five best universities in the world.

Bees play a vital role in the ecosystem, pollinating plants and ensuring food production. Bees provide us with valuable products that have been used for millennia in both cooking and body care such as honey, pollen, royal jelly, propolis, wax, and even poison.

However, bees are threatened from many sources, including habitat loss, pesticide use and climate change.

It is important that we all take steps to protect bees and their environment.

In this photo gallery, we offer eight practical tips to save bees.

Flooding can cause significant damage to homes and result in significant repair costs.

Preventing flooding in the home is essential to ensure the safety of your family and the protection of your property.

In this article, we will provide useful instructions on how to avoid flooding in the home and minimise the risk of water damage.

History is unfortunately full of episodes in which natural catastrophes have claimed a very high number of victims.

Looking at the case history, among the main causes that have triggered natural disasters throughout history are earthquakes, followed by floods and cyclones. These are natural phenomena beyond the control of man, who often manages to do very little, even in terms of prevention, against them.

The downside of all this is, of course, the high number of victims and the destruction that such phenomena generally entail. Often, in both cases, with devastating effects of great magnitude. (source: livescience)

Each of us may go through moments of uncertainty at work, and recognising these signs could be crucial in preparing for change.

We have explored gestures, behaviours and situations that could indicate a threat to your job position, with the aim of providing awareness and inspiration to react positively in such circumstances.

Some of these situations taken individually may not be indicative of such a drastic consequence as dismissal, but taking a moment to carefully observe each situation and reflect on your personal experience is nevertheless a way to prevent unpleasant situations from occurring.

In some of these cases, however, one is not appreciated and one is not to blame for this: if it happens, it is good to look around for a new opportunity.

It may sound like a trivial question, but in fact it is not trivial at all; on the contrary, it holds within it very important physical and philosophical questions. The Washington Post noted that this question is stirring up some of the people on Twitter these days.

The debate was generated by a tweet from journalist Jacqui Deevoy, who wondered how it was possible that the sun had 'changed colour' from what she remembered as a child. The answer, however, is one that leaves one somewhat appalled, as there is no real unequivocal answer.

After all, children do not make a mistake by drawing the sun as a big yellow ball, but it is not a completely right answer. After all, light is just the perception of the wavelength of radiation emitted by the sun, and therein lies the whole secret.

A large part of human activities that can have an impact on the environment is carried out at sea (fishing, maritime transport, coastal tourism), in the oceans and on their shores. This obviously has a very negative impact on the environment if citizens and companies are not educated to be more respectful of the waters.

The 'Blue Economy' is a key project for the European 'Green Deal', obviously a series of measures to make energy production and the lifestyle of citizens throughout Europe more sustainable and less environmentally damaging.

The 'Blue Economy' not only focuses on reducing pollution and more sustainable exploitation of the seas in the long term, but also offers enormous potential for economic and job growth for all European citizens. Already 4.5 million people on the Continent are engaged in it, and much more work could come.