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Colorless diamonds can command high prices as gemstones

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Colorless diamonds can command high prices as gemstones

by RBBmba@2014 » Wed May 04, 2016 7:44 am

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Colorless diamonds can command high prices as gemstones. A type of less valuable diamonds can be treated to remove all color. Only sophisticated tests can distinguish such treated diamonds from naturally colorless ones. However, only 2 percent of diamonds mined are of the colored type that can be successfully treated, and many of those are of insufficient quality to make the treatment worthwhile. Surely, therefore, the vast majority of colorless diamonds sold by jewelers are naturally colorless.

A serious flaw in the reasoning of the argument is that

(A) comparisons between the price diamonds command as gemstones and their value for other uses are omitted

(B) information about the rarity of treated diamonds is not combined with information about the rarity of naturally colorless, gemstone diamonds

(C) the possibility that colored diamonds might be used as gemstones, even without having been treated, is ignored

(D) the currently available method for making colorless diamonds from colored ones is treated as though it were the only possible method for doing so

(E) the difficulty that a customer of a jeweler would have in distinguishing a naturally colorless diamond from treated one is not taken into account

OA:B

Source: OG Verbal 2016,CR Qs.62

@Verbal Experts - I got this completely wrong,chose E. Please share your analysis for this CR.
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by OptimusPrep » Wed May 04, 2016 8:22 pm

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RBBmba@2014 wrote:Colorless diamonds can command high prices as gemstones. A type of less valuable diamonds can be treated to remove all color. Only sophisticated tests can distinguish such treated diamonds from naturally colorless ones. However, only 2 percent of diamonds mined are of the colored type that can be successfully treated, and many of those are of insufficient quality to make the treatment worthwhile. Surely, therefore, the vast majority of colorless diamonds sold by jewelers are naturally colorless.

A serious flaw in the reasoning of the argument is that

(A) comparisons between the price diamonds command as gemstones and their value for other uses are omitted

(B) information about the rarity of treated diamonds is not combined with information about the rarity of naturally colorless, gemstone diamonds

(C) the possibility that colored diamonds might be used as gemstones, even without having been treated, is ignored

(D) the currently available method for making colorless diamonds from colored ones is treated as though it were the only possible method for doing so

(E) the difficulty that a customer of a jeweler would have in distinguishing a naturally colorless diamond from treated one is not taken into account

OA:B

Source: OG Verbal 2016,CR Qs.62

@Verbal Experts - I got this completely wrong,chose E. Please share your analysis for this CR.
Hi RBBmba@2014,

Premise: Colourless diamonds are as expensive as gemstones
Less valuable coluored diamond can be treated to make it colorless
Very few coloured diamonds are available

Conclusion: Sine very few coloured diamonds are available, diamonds sold by jewellers are colourless and not counterfeit.

We need to weaken this conclusion.
The conclusion easily assumes that the colourless diamonds are available in abundance. What it they are also rare. In this case, counterfeiting is always a possibility. Hence we need to establish first that natural colourless diamonds are not in shortage.

Option B says just the same by talking about the rarity of colourless diamonds.
Hence the correct answer

Coming to option E, we are no concerned about the difficulty to distinguish. We are concerned about how widespread the counterfeit ones can be. This is out of scope.

Does this help?
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by RBBmba@2014 » Mon May 09, 2016 1:32 pm

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Hi,
While I understand why B is the OA, although a quick question on the OA -- Won't it make more sense to use the word COMPARE instead of the word COMBINE in B ?

I'm still having difficulty why E is NOT a flaw in the reasoning of the argument ?

If E is true then it seems that the jewelers would perceive as if they're selling naturally colorless diamonds at the time of selling ARTIFICIALLY colorless diamonds to customers. Thus it'll incorrectly inflate the count/proportion of naturally colorless diamonds sold,though actually this proportion is less!
Last edited by RBBmba@2014 on Thu Jun 02, 2016 8:26 am, edited 1 time in total.
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by DavidG@VeritasPrep » Wed Jun 01, 2016 7:50 am

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RBBmba@2014 wrote:Hi,
While I understand why B is the OA, although a quick question on the OA -- Won't it make more sense to use the word COMPARE instead of the word COMBINE in B ?

I'm still having difficulty why E is NOT a flaw in the reasoning of the argument ?

If E is true then it seems that the jewelers would perceive as if they're selling naturally colorless diamonds at the time of selling ARTIFICIALLY colorless diamonds to customers. Thus it'll incorrectly inflate the count/proportion of naturally colorless diamonds sold,though actually this proportion is less!



P.S: Other Verbal Experts (Dave/Mitch/Ceilidh) - could you please shed light on this ?
Boiled way down, here's the argument: 2% (or less) of the diamonds that are mined are candidates to be made into counterfeit colorless diamonds. Therefore, the vast majority of the colorless diamonds sold are not counterfeit.

Notice the switch in language. If we were to reach into a bag of 100 freshly mined diamonds, there's a 2% chance (or less) that we'd select a potentially counterfeit colorless diamond. But that's not the relevant figure in the conclusion. The relevant figure is the probability that we'd select a counterfeit colorless diamond from a bag of colorless diamonds, not from a bag of diamonds in general.

Consider two simple scenarios. Scenario 1: of 100 diamonds there are 2 counterfeit colorless diamonds, and 98 authentic colorless diamonds. In this case, if you were to select a seemingly colorless diamond at random, there'd be a 2% chance of grabbing a counterfeit colorless diamond, as all 100 diamonds in this sample appear to be colorless, and 2 are fake.

Scenario 2: of 100 diamonds, there are 2 counterfeit colorless diamonds, 1 authentic colorless diamond, and 97 other diamonds. Now, there are only 3 diamonds total that appear to be colorless. So if you were to randomly pick a diamond that appeared to be colorless, there's a 2/3 or 66.67% chance of grabbing a counterfeit.

So we have to know what percentage of diamonds overall are colorless to know the odds of selecting a counterfeit diamond from a population of colorless diamonds.

E surely isn't a flaw in the reasoning. Imagine that it's true that customers can't tell the difference between fake and authentic colorless diamonds. If Scenario 1 were true, the vast majority of colorless diamonds sold would still be authentic simply because the fakes represent such a tiny percentage of the colorless population.
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by RBBmba@2014 » Thu Jun 02, 2016 8:15 am

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Hi Dave,
I can understand why Option B is OA and your above analysis for the OA is really great. However, couple of quick questions:

1. NOT able to understand your explanation on E COMPLETELY. For Scenario 2 that you described above, E stands viable, I guess.
Accordingly, why it doesn't INDICATE a FLAW in the ARGUMENT STILL ? Please clarify.

And btw, as a STANDALONE choice, can we anyhow classify E as a POTENTIAL WEAKENER on GMAT front (on the basis of my analysis on E in this post - https://www.beatthegmat.com/colorless-di ... tml#771688)

2. Could you please shed light on how EXACTLY finding FLAW questions are DIFFERENT from WEAKENING questions ? How basically the approach differs from dealing a FLAW CR to WEAKEN CR on GMAT ?
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by DavidG@VeritasPrep » Thu Jun 02, 2016 9:37 am

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RBBmba@2014 wrote:Hi Dave,
I can understand why Option B is OA and your above analysis for the OA is really great. However, couple of quick questions:

1. NOT able to understand your explanation on E COMPLETELY. For Scenario 2 that you described above, E stands viable, I guess.
Accordingly, why it doesn't INDICATE a FLAW in the ARGUMENT STILL ? Please clarify.

And btw, as a STANDALONE choice, can we anyhow classify E as a POTENTIAL WEAKENER on GMAT front (on the basis of my analysis on E in this post - https://www.beatthegmat.com/colorless-di ... tml#771688)

2. Could you please shed light on how EXACTLY finding FLAW questions are DIFFERENT from WEAKENING questions ? How basically the approach differs from dealing a FLAW CR to WEAKEN CR on GMAT ?
A couple ways to think about this. First, if an answer choice only functions as a weakener under very specific circumstances that we cannot necessarily expect to prevail, it's wrong.

Second, we're not only focusing on the conclusion. We want to pay attention to the way the evidence leads to the conclusion. In this case, the author is using the fact that 2% (or less) of mined diamonds diamonds are counterfeit, to argue that a small % of sold colorless diamonds will be counterfeit. So the question isn't simply about whether the author is correct that a small % of colorless diamonds will be counterfeit, but whether considering this 2% figure is, in fact, a valid way to draw this conclusion. Put another way, it's not just about whether the author's conclusion might be incorrect. It's a question about statistical inference, and how one figure may not be sufficient evidence to forecast another figure. Taken this way, E is out of the argument's scope.
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by DavidG@VeritasPrep » Thu Jun 02, 2016 10:03 am

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2. Could you please shed light on how EXACTLY finding FLAW questions are DIFFERENT from WEAKENING questions ? How basically the approach differs from dealing a FLAW CR to WEAKEN CR on GMAT ?
Some books will actually treat "flaw" questions as a subcategory of "weaken" question. As for how my approach differs, it's pretty subtle. For a weaken question, I'm internalizing the conclusion, noting the premise(s), spending a moment or considering the gap between the two, and then hitting the answer choices quickly. For a flaw question, I know the argument is either illogical or is missing something important, so I'll spend more time considering what that might be before going to the answer choices. Put another way, I find that the answer to a weaken question is a little harder to predict than the answer to a flaw question.

Take a really simple weaken argument. In town X, there is great demand for widgets. Tim, who plans to start a widget business in town x, will soon be rich.

This argument could be weakened in a lot of different ways. Maybe Tim's widgets are inferior to his competitors; maybe widget customers are losing their jobs in record numbers and will soon curtail their widget consumption; maybe margins on widgets are so small that it's difficult to turn a profit even if you're selling a lot of products; maybe some zoning ordinance will force Tim to move to a town with lesser widget demand; maybe everyone in Town X hates Tim and boycotts his business, etc. You get the idea.

Now take a simple flaw argument: Tim owns a business. His market share this year is down 10 percentage points from what it was last year. Therefore, his business is struggling.

If I'm looking for a flaw, I know that the author has missed something important. In this case, there's no mention of market size from year to year. I'd rather have 5% of a $10,000,000 market then have 15% of a $100,000 market. I'll make sure to note this before going to the answer choices. That's the main difference in my approach.
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by nchaswal » Thu Jun 02, 2016 11:17 am

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RBBmba@2014 wrote:Hi Dave,
I can understand why Option B is OA and your above analysis for the OA is really great. However, couple of quick questions:

1. NOT able to understand your explanation on E COMPLETELY. For Scenario 2 that you described above, E stands viable, I guess.
Accordingly, why it doesn't INDICATE a FLAW in the ARGUMENT STILL ? Please clarify.

And btw, as a STANDALONE choice, can we anyhow classify E as a POTENTIAL WEAKENER on GMAT front (on the basis of my analysis on E in this post - https://www.beatthegmat.com/colorless-di ... tml#771688)

2. Could you please shed light on how EXACTLY finding FLAW questions are DIFFERENT from WEAKENING questions ? How basically the approach differs from dealing a FLAW CR to WEAKEN CR on GMAT ?
Hi

When I tried solving this question, I also narrowed down to the options B and E. I went ahead with E only. This is a tricky choice and if you DO NOT read closely you will surely miss the reason why E is NOT the correct choice.

If you read closely, the prompt says "Only sophisticated tests can distinguish such treated diamonds from naturally colorless ones". This automatically tells you that the "difficulty a customer would face in distinguishing between a fake colourless diamond and a real colourless diamond" is ALREADY taken into account as when ONLY sophisticated tests can distinguish between them, a CUSTOMER would surely not be able to distinguish between them. HENCE, E is incorrect.

Therefore you are left with B. B is kind of similar to weaken the argument but not totally.

The prompt says: As fake colourless diamonds are very less in quantity(Cause) -> Rest of the diamonds should be natural (Effect)

To weaken, you either tell :-

(I) The Cause is there but the effect is not i.e. Any statement which tells that though fake colourless diamonds are there but rest of the diamonds are not natural colourless.

Or

(II) Effect is there when the cause is not i.e. There are a lot of natural colourless diamonds but fake diamonds are also in abundance.

As the second statement is not possible as given in the prompt, you will look for first kind of statement and that is answered only by B which tells the information about rarity of natural diamonds is not provided.

Hope you get why E is wrong.

Also finding the flaw is equivalent to finding the unsaid premises i.e. assumption which if false will crash the argument. OR an assumption which author assumes but has not said. Any assumption if proven wrong can crash the argument. So in finding the flaw you are just saying WHAT WAS THAT WHICH AUTHOR DID NOT TAKE INTO CONSIDERATION.

Whereas, in WEAKEN the argument, the statement which author did not take into consideration is GIVEN RIGHT IN FRONT OF YOU.

Flaw is more like, If author had provided THIS SPECIFIC information this argument would have been more valid

Whereas, in weaken, the correct option is taken as TRUE and then argument is evaluated.

Let me know if further explanation is needed
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by RBBmba@2014 » Fri Jun 03, 2016 3:25 am

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Hi Dave,
Thanks for the detail clarifications. So what I understand from your above two replies is:

For "finding FLAW" CR, the FLAW itself is sort of embedded in the ARGUMENT. In other words, it's already hidden in the REASONING on the basis of which the Evidence/Premise in the ARGUMENT leads to the Conclusion.

Whereas, in a WEAKEN CR, we need to find an information which is NOT present in the STIMULUS,but within the SCOPE of the ARGUMENT and this outside (but in scope) INFORMATION/PREMISE would WEAKEN the Conclusion by attacking the LINK between the PREMISE and the CONCLUSION of the ARGUMENT.

Did I get you right ?

P.S: Btw, I guess, it'll be better to comprehend if we use drop by TEN PERCENTAGE POINTS (instead of simply drop by 10%) in the "market share argument" that you cited above for FLAW CR. Isn't it ?
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by DavidG@VeritasPrep » Fri Jun 03, 2016 7:10 am

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For "finding FLAW" CR, the FLAW itself is sort of embedded in the ARGUMENT. In other words, it's already hidden in the REASONING on the basis of which the Evidence/Premise in the ARGUMENT leads to the Conclusion.

Whereas, in a WEAKEN CR, we need to find an information which is NOT present in the STIMULUS,but within the SCOPE of the ARGUMENT and this outside (but in scope) INFORMATION/PREMISE would WEAKEN the Conclusion by attacking the LINK between the PREMISE and the CONCLUSION of the ARGUMENT.

Did I get you right ?
You sure did.
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by DavidG@VeritasPrep » Fri Jun 03, 2016 7:11 am

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P.S: Btw, I guess, it'll be better to comprehend if we use drop by TEN PERCENTAGE POINTS (instead of simply drop by 10%) in the "market share argument" that you cited above for FLAW CR. Isn't it ?
Now that is the kind of attention to detail that will serve you well :) (I've edited my earlier post accordingly.)
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Re: Colorless diamonds can command high prices as gemstones

by Doryhihii » Thu Dec 30, 2021 8:17 am

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Hi @ GMATGuruNY, could you please help me on this? Thank you.
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