Turn a gem into a polysurface


I want to convert a gem into a polysurface,
I was used to explode the gem and then I could boolean them with other polysurfaces.

But now I get the message"that explode a gem is a bad idea" and i won’t work anymore.
How can I solve this?

Kind regards,


hi @francis,

can you provide a example? are you talking about a scanned gem (like sarine scan) as stl or a old matrix/gem tech gem and used explodeBlock?


Hi Ben,

It is a gem from Matrixgold (attachment) I want to convert.

Kind regards,


gem.3dm (312 KB)

This is a block which contains a single mesh. Explode the block, then use _MeshToNurb to convert it to a polysurface, then _MergeAllCoplanarFaces to clean it up.

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nice, my swiss neighbour gave the perfect answer

Sorry, but it doesn’t work…

I can’t explode the gem.

try the command:

instead of


Perfect :blush:

Thank you for solving this

Kind regards,


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Dunno, the normal _Explode command works fine here to explode the block instance. What version of Rhino are you using?


I use Rhino 7.

But the problem is solved.

I had to use the “explodeblock” command instead of the “explode” command.

I’m really grateful for your help.

Kind regards,