I have troubles with using but in the particular example I made by myself below:

Many types of metals can be damaged by water but diamond can't

Diamond can't be damaged by water but many types of metals can

The reason I use either "but something can/can't" is because I want to avoid repetition (such as "many metals can be damaged with water but diamond can't be damaged with water"). Is it grammatically correct if I omit "be + verb 3/verb+ed"?

Thank you


2 Answers 2


Yes this is perfectly fine. My person preference is to change this to the simple present tense rather than the conditional:

Many metals are damaged when exposed to water, but diamond is not.

The simple present is used to indicate something that is a general truth.

(Edit) Many native speakers are uncomfortable with my example sentence, first because the use of "diamond" rather than "diamonds" seems to break the style rule of parallelism. While I agree the syntax is a little strange, in this context it's fine because "diamond" is the (uncountable) material, while "diamonds" are the cut gemstones made from the material. Consider:

The foolish man sunk his entire inheritance into a diamond mine. (not a diamonds mine).

"Metal", similarly, refers to various (uncountable) substances, some of which can be damaged by water (iron, etc.) and some which can't (gold, etc.). So comparing one set of substances to another substance is perfectly parallel.

Some native speakers also feel this sentence implies diamond is a metal. Ordinarily, if forced to make this comparison) I would include some kind of disclaimer to avoid any confusion:

Many metals are damaged by water, but diamond (which is not a metal) is not.

In addition, a friend pointed out this sentence unnecessarily uses the passive voice, which I could avoid by changing the verb:

Many metals corrode/oxidize in water, but diamond does not.

Finally: I don't understand why OP is comparing metals to diamond, which is a crystal. Chemically they are different enough that few would expect them to share similar physical properties. But since that's off-topic in a forum on English Language, I'll let it slide.

  • Andrew, diamonds cannot. The plural is de rigueur.
    – Lambie
    Mar 30, 2018 at 14:08
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    @Lambie: diamond is also the substance and can be used in the singular. Mar 30, 2018 at 14:09
  • "Highly boron-doped diamond has been recognized as a promising electrode material in electrochemistry because of its attractive properties, including very low background currents, wide electrochemical potential window in aqueous media, and chemical inertness" Mar 30, 2018 at 14:24
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    Diamond as an uncountable noun meaning "a particular allotrope of carbon" is perfectly acceptable usage. It is in fact the very first definition at dictionary.com. Compare to other carbon allotropes such as graphite, which is also an uncountable noun. Mar 30, 2018 at 15:16
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    @Ronald Sole: Some laymen, perhaps, might find the absence of the article grating there, but that's because they're set in their own context, in which "a diamond is a kind of gem stone". I like moose might sound strange to someone who does not eat it regularly. Mar 30, 2018 at 15:44

Your pattern is perfectly idiomatic, and you're executing it properly, but there are other ways of stating such a fact.

Unlike metals, diamonds cannot be damaged by water.

Diamonds cannot be damaged by water, unlike metals, which oxidize.

Unlike metals, which oxidize, diamonds cannot be damaged by water.

Water does not damage diamonds as it does metals.

That last one is a tad ambiguous — it could be understood that there is some damage to the diamond, just a different sort of damage. Further explanation would clear that up, of course.

  • Do you think there is a difference between "Many types of metals" and "Many types of metal"? I wonder if using diamonds/metals or diamond/metal instead of diamond/metals is more idiomatic. It does seem a bit curious that you switched from diamond to diamonds in your alternate phrasings.
    – ColleenV
    Mar 30, 2018 at 15:42
  • @Lambie: I understand that. I added my comment beneath Andrew's answer when you told him that the singular was wrong. My answer here focuses on the clausal patterns. The singular/plural issue is not germane to the OP's actual question. Mar 30, 2018 at 15:47
  • Are there different kinds of diamond like there are different kinds of metal in nature ?
    – FrankMK
    Mar 30, 2018 at 16:50

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