Diamonds В4 Diamonds are a symbol of luxury for many people. People _____ VALUE diamonds as attractive jewellery for around 2,500 years. The Indians used them to decorate religious icons and it seems the ancient B5 Chinese their axes a sharp edge using diamonds. GIVE B6 Diamond is the hardest substance on Earth, that only MEAN another diamond can be used to cut a diamond. B7 Diamonds consist of carbon and usually they deep FIND underground in mines, but you might get lucky and see them on the surface. B8 Mining_____________ in places like Africa make a lot of money COMPANY from diamonds. B9 However, the miners______________ are often quite poor. THEY BIO The value of a diamond is judged on four criteria._______________ KNOW as the four Cs: carat (or size), clarity, colour and cut. Bl1 The diamond ever found was the Cullinan diamond, HEAVY which was discovered in 1905 and weighed 621 grammes.

Вот как заполняются пропуски (с пояснениями по грамматике и словообразованию):

B4: have valued
People have valued diamonds as attractive jewellery for around 2,500 years.
→ Present Perfect (действие началось в прошлом и продолжается до сих пор) + глагол по смыслу от VALUE.

B5: gave
…it seems the ancient Chinese gave their axes a sharp edge using diamonds.
→ Past Simple от GIVE для описания законченного факта в прошлом.

B6: which means
Diamond is the hardest substance on Earth, which means only another diamond can be used to cut a diamond.
→ Относительное местоимение which + Present Simple от MEAN для пояснения факта.

B7: are found
Diamonds consist of carbon and usually they are found deep underground in mines…
→ Страдательный залог (их «находят»), форма Present Simple Passive от FIND. Наречие deep остаётся на своём месте.

B8: companies
Mining companies in places like Africa make a lot of money from diamonds.
→ Множественное число от COMPANY.

B9: themselves
However, the miners themselves are often quite poor.
→ Усилительное местоимение от THEY — подчёркивает контраст.

B10: known
The value of a diamond is judged on four criteria, known as the four Cs: carat, clarity, colour and cut.
→ Причастный оборот от KNOW (по смыслу — «известные как…»).

B11: heaviest
The heaviest diamond ever found was the Cullinan diamond, which was discovered in 1905 and weighed 621 grammes.
→ Суперлатив от HEAVY для «самый тяжёлый».