We are often asked about refiners, and where to send samples
for assays. While we don't make recommendations, we have
posted the following links for your education.
This is a BLM study on the ability of individuals/labs to properly
conduct assays. Essential reading before you get a sample
tested. Originally printed in the ICMJ, and posted here with
their permission:
Preface (pdf)* Study signatories, Introduction, Assays
Generally, Survey Methods, Standard and Blanks Used,
Interpreting Results
Study Results (pdf)*
* requires Acrobat Reader