It is haraam for a man to wear natural silk, but it is permissible to wear it for the purpose of medical treatment. As for artificial silk, there is nothing wrong with wearing it. So he should look at the satin, and if it is made with natural silk, then it is haraam to wear it, but if it is artificial, then it is permissible to wear it.

It is obligatory for the man to cover his ‘awrah, which is the area between the navel and the knees, except from his wife or concubine. The ‘awrah is to be covered with that which does not show its colour or shape, because if either of these two can be discerned, then it is not covering and temptation could result from looking at it. The guideline on showing the shape of the ‘awrah, which is prohibited, is that this refers to wearing tight garments that show the shape of the ‘awrah and the details of the limbs, buttocks, penis and thighs. Some of these trousers are so bad that it cannot be imagined that any wise person could wear them in front of men or women. As for loose trousers that do not show that, there is nothing wrong with wearing them. For more details, please see the long answer.

With regard to necklaces, it is not known that this custom is widely practiced among men without any objection; rather hardly anyone does it except effeminate men and their ilk, or those who imitate women or evildoers. So it is not permissible for you to wear it for that reason.

It is permissible to wear white, red, yellow, green, striped and other colours of clothing, and there was no difference of opinion concerning that, and none of them are makruh. It is also permissible for women to wear whatever colours they like, so long as they do not display themselves in front of non-mahram men.