1.diamond的基本意思是“钻石,金刚石”,指一种已知的最坚硬的矿物质,可用于多种用途(如装饰首饰等); 还可以指类似于方块状,但又不是完全直角的形状,即“菱形”。diamond还可用来指纸牌游戏中的“方块”。
2.diamond多为可数名词,当作“金刚石,钻石”解时也可用作不可数名词。

a diamond in the rough
外粗内秀的人 a man looks rude but his〔her〕 heart is good
He is honest, though a bit rude. I shall call him a diamond in the rough.他为人诚实,但有些粗鲁,可以说是一个外粗内秀的人。

diamond cut diamond
棋逢对手 a game that none of the number can win
There will be a volleyball semi-final between “the Eagle” and “the Tiger”. That will really be diamond cut diamond.鹰队和虎队之间将进行排球半决赛,这将是一场真正的棋逢对手的比赛。
It was diamond cut diamond when the two men met because they were both so sure their own ideas were right.那两人一交锋真是棋逢对手,互不相让,因为他们都确信自己的想法是正确的。

diamond of the first water
第一流的好人 the best man
He is a diamond of the first water, always obliging.他是第一流的好人,总是乐于帮助别人。
“Oh, thank you!” she enthused gratefully. “You're a real gem, a diamond of the first water.”“谢谢!”她表示感激热情洋溢地说,“你真是一个被人尊敬的人,第一流的好人。”

The diamond sparkles with brilliant light.钻石闪烁出灿烂的光芒。
It's a synthetic diamond.这是人造钻石。
The ring has a diamond in it.这枚戒指上镶着一颗钻石。
He gave her a diamond ring on the day when they were engaged.他们订婚那天他送她一枚钻石戒指。
These diamonds are fake.这些钻石是假的。
Shall I wear my diamonds tonight?我今晚要戴钻石首饰吗?
Things such as diamonds are expensive to buy.钻石这类的东西是很贵的。
The value of diamonds has gone up in recent years.近年来钻石的价格上涨了。
They are in a great need of industrial diamonds.他们需要大量的工业用金刚石。
This is a diamond.这是菱形。
It was made of three diamonds.它由3个菱形组成。
Diamonds are trumps.方块为王牌。
I've got only four diamonds in my hand.我手里仅有4张方块牌。

［词源］  ＜古法语diamant(金刚石)