If it's really small and nano, it will be yellow and not sediment.  Indeed if it sediments, it's not colloidal or nano (< 100 nm).  See:

September 2nd, 2015 Silver colloids and invisible ink

https://www.brainshark.com/malvern/vu?pi=560497681&b=1&tx=120486&c1=22

and:

Nov 11th, 2008. Dispersion and nanotechnology  http://tinyurl.com/hpywsge

If it's small and effectively spherical  then it'll be a transparent yellow and looking like a solution.  See slide 43 in:

February 18th, 2016 Metal colloids - their preparation, application and characterization

https://www.brainshark.com/malvern/vu?pi=529368070&b=1&tx=120486&c1=22

 No amount of centrifuging will cause precipitation in this case.

Hi

for small NPs, you should use ultra-centrifuge. However, you may not be able to capture all of the particles and the amount of loss is indirectly proportional to the size of NPs. 

BR

Mohammad