Is there a rule of thumb for double stops on the cello?

I am writing a piece for cello and piano and I'm wondering, is there any rule of thumb as to which double stops are easy and which ones are difficult on the cello? I know that for example an octave double stop is harder on cello than on violin, but how much harder? I have no experience playing a bowed string instrument, so all I really know is this:

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Some double stops are harder than others. On violin, a twelfth might be okay, but I should probably avoid that on cello, even if there are cellists that can play such wide intervals, not just because of how much bigger the cello is, but also due to more contrast in timbre in each octave of the cello's range. And with double bass, I can't even trust that the octave is a possibility, let alone know which octaves are more difficult than others. Thirds are okay all the way down to F2 as the lower note of the interval. Sixths, also okay, even with the lowest note being C2. But what about sevenths? Fifths(outside of open string double stops)? Fourths? Are fifths harder than sixths? Are sevenths easier than fourths? How much more difficult are octave double stops on the cello compared to the violin?

I have tried looking up charts of possible double stops, but I rarely find them for violin, so it would probably be even rarer for cello, despite the similar commonality of the 2 instruments. So, I can't just look it up online and write down the double stops in order of easy, intermediate, difficult, not just because of the rarity of double stop charts, but also the variability in the size of the cellist's hand. On the violin, this hand size variability is a non-issue, as most double stops an octave or smaller are easy enough. Not so for the cello.

So, is there a rule of thumb when it comes to writing double stops for the cello as to which ones will be easier for intervals other than thirds or sixths? Because, I have this harmonic moment here in my piece(which, by the way, is in C major) around bar 8:

I know the third is easy, but what about the preceding diminished fifth? How hard is that? You see why I am wanting a rule of thumb for double stops besides thirds and sixths such as fourths, fifths, and octaves?

What is the tempo?

how I can explain this... The stops should be play on each string without shifting. So can you play C3 and E3 on the C and G string respectively and then play G3 and C4 on the D and A string without shifting?   To my knowledge  No? 

As a general rule, most double stops are okay up to an octave. In the low register, many cellists use their thumb to reach the bottom note. As you get higher, the notes are closer together so larger intervals are easier.

2 hours ago, caters said:

Some double stops are harder than others. On violin, a twelfth might be okay, but I should probably avoid that on cello, even if there are cellists that can play such wide intervals, not just because of how much bigger the cello is, but also due to more contrast in timbre in each octave of the cello's range. And with double bass, I can't even trust that the octave is a possibility, let alone know which octaves are more difficult than others. Thirds are okay all the way down to F2 as the lower note of the interval. Sixths, also okay, even with the lowest note being C2. But what about sevenths? Fifths(outside of open string double stops)? Fourths? Are fifths harder than sixths? Are sevenths easier than fourths? How much more difficult are octave double stops on the cello compared to the violin?

Right, let's have a look at this.

1. Twelfths on violin? It's going to be extremely difficult. Possible in the high notes, but consider that a short passage of tenths in Tchaikovsky's violin concerto is considered one of the hardest double stoppings.

2. Good point about the contrast of timbre. However, string instruments are rich in overtones, so octaves blend better than you might think - the lower note reinforcing the upper and vice versa.

3. Double bass double stops are a no-no, unless one of them is an open string. Even then, it's going to sound odd.

Twelfths on Violin are impossible unless an open string is involved. Otherwise, violinist can only play tenths. 

8 hours ago, maestrowick said:

What is the tempo?

The tempo of my piece is quarter note = 65 BPM, though with all the sixteenths I am writing for the piano, it is turning out to sound more like an Allegro than an Adagio, making me consider changing the time signature to an eighth note time signature.

NEVER do 12ths.  My wife says more than an octave is a no-go.

Hello! I am new to the forum. I wish to becoming a contributing member and intend to add more of myself regularly to this forum.

I'm in my mind 30's, hoping to enter a master's program in composition; some of my challenges on the way comes with the fact that my undergraduate studies wasn't in composition, which I now regret later in life. 

Amid building my profile, I am writing a string quartet, which the 6th and final movement is enamored with heavy double-stops and triple-stop rolls and tremolos. 

I'm glad I came across this thread. For my inquiry, please observe the following cello passages mentioned in pg. 2 of my piece. Is this fast octaves-motif viably doable?

meter: 5/8

tempo: 8th=156

Fast thirds require thumb, but after 4th position are easier. octaves are fine. Tenths start on 4th position (same pitch as the higher open string) as in the cello transcription for Paganini's 24th caprice. unisons (for small hands) should start an octave above the lower open string. Fifths, unlike violin and viola, are played like barre on guitar. 

only bad part is that double A unison, but it does exist in some cello pieces 

link to a sheet music video of paganini's 24th caprice played by Yo Yo Ma:

Hello, ChemathMusician0510,

I realized just now that you were replying to my inquiry. Thanks so much for your insightful advice. I've actually since removed the double-stop, as I found simpler single-stop "Bach-like"-mimics and methods that did the job nearly identically well. But, for my future reference, I'm glad to know that 8v-double-stops like this work. On the other hand, it is located on the lower range of the Cello. From my understanding, this would mean that the hand will have to be stretched. My guess is that some people would say that this is not viable at all. Is this true of the range that I wrote? Or, are you sticking to what you said: that it should be fine?

Also, I came across a low stringist who too advised me against the A-flat double-unison. And, so, it too was removed.

Cheers,

ARCMusicPublishings

p. s. The dream school which the final draft of this piece has been submitted to? It has earned me my admission there, which I was greatly excited about. 😃

I have small hands compared to other cello players. so if it works for me, it works for most other cellists. Just keep in mind that sometimes 8v double stops with one open string are harder to do if all the other double stops around it don't need open string. Jumps in octaves are also harder, but a good cellist should be able to pull it off. (studies in octaves in scale patterns or arpeggios are usually a staple for any good cellist)

(Currently trying to compose pieces for college admissions. My cello experience consists having three teachers with years of time between first and second teacher and the last teacher is a violinist)