A buoy suspension fractionation system, comprising: a separation container having a central axis and enclosed by a container wall, a container bottom and a container top; an access port through a portion of the separation container; and a buoy in the separation container, the buoy having a tuned density and configured to reach an equilibrium position in a suspension, the buoy comprising: a buoy sidewall (38, 40) defining a maximum width therebetween along a first plane substantially perpendicular to the central axis, a buoy upper surface, and a buoy bottom surface, the buoy sidewall having at least a first sidewall height at a first perimeter position and a second sidewall height at a second perimeter position, the buoy upper surface oriented transverse to the buoy sidewall; a guide surface defined by the buoy upper surface, the guide surface inclined at a first angle (alpha) relative to the central axis from the first perimeter position to the second perimeter position at an accumulation position near the perimeter; and a precision collection surface interposed between the guide surface and the accumulation position and defined by the buoy upper surface inclined at a second angle (beta) relative to the central axis, wherein the second angle is smaller than the first angle. a separation container having a central axis and enclosed by a container wall, a container bottom and a container top; an access port through a portion of the separation container; and a buoy in the separation container, the buoy having a tuned density and configured to reach an equilibrium position in a suspension, the buoy comprising: a buoy sidewall (38, 40) defining a maximum width therebetween along a first plane substantially perpendicular to the central axis, a buoy upper surface, and a buoy bottom surface, the buoy sidewall having at least a first sidewall height at a first perimeter position and a second sidewall height at a second perimeter position, the buoy upper surface oriented transverse to the buoy sidewall; a guide surface defined by the buoy upper surface, the guide surface inclined at a first angle (alpha) relative to the central axis from the first perimeter position to the second perimeter position at an accumulation position near the perimeter; and a precision collection surface interposed between the guide surface and the accumulation position and defined by the buoy upper surface inclined at a second angle (beta) relative to the central axis, wherein the second angle is smaller than the first angle. a buoy sidewall (38, 40) defining a maximum width therebetween along a first plane substantially perpendicular to the central axis, a buoy upper surface, and a buoy bottom surface, the buoy sidewall having at least a first sidewall height at a first perimeter position and a second sidewall height at a second perimeter position, the buoy upper surface oriented transverse to the buoy sidewall; a guide surface defined by the buoy upper surface, the guide surface inclined at a first angle (alpha) relative to the central axis from the first perimeter position to the second perimeter position at an accumulation position near the perimeter; and a precision collection surface interposed between the guide surface and the accumulation position and defined by the buoy upper surface inclined at a second angle (beta) relative to the central axis, wherein the second angle is smaller than the first angle.