A very attractive and expensive allotrope of carbon is diamond,the diamond is an extremely hard material found on earth ,it is one of the hardest minerals.What makes diamonds valuable is because of its appearance and rarity ,and for centuries diamonds have been regarded as the most brilliant of precious stones,for when they cut they are particularly attractive in the way they reflect light,and now the diamonds are being used in the manufacturing of jewelery and for fashion.There has been a demand ever since!

Thanks Rabieh,this topic will help your friend extend their information about the new chemistry lesson.Go ahead

Diamonds also tend to be very expensive

well,acube of volume 1cm^3 of diamond can buy a cube of another allotrope of carbon,graphite,of abou a volume of 1000000cm^3.The previous given information in this reply is a personal prediction, and not a fact.

wow, how do you know so much? they must teach you a lot at 14