Matters Arising | Published:

Reply to: Evidence for two blue (type IIb) diamond populations

Access optionsAccess options

Rent or Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.

Additional information

Publisher’s note: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.


  1. 1.

    Smith, E. M. et al. Blue boron-bearing diamonds from Earth’s lower mantle. Nature 560, 84–87 (2018).

  2. 2.

    Walter, M. J. et al. Deep mantle cycling of oceanic crust: evidence from diamonds and their mineral inclusions. Science 334, 54–57 (2011).

  3. 3.

    Stachel, T., Harris, J. W., Brey, G. P. & Joswig, W. Kankan diamonds (Guinea). II: Lower mantle inclusion parageneses. Contrib. Mineral. Petrol. 140, 16–27 (2000).

  4. 4.

    Thomson, A. et al. Origin of sub-lithospheric diamonds from the Juina-5 kimberlite (Brazil): constraints from carbon isotopes and inclusion compositions. Contrib. Mineral. Petrol. 168, 1081 (2014).

  5. 5.

    Moore, A. & Helmstaedt, H. Evidence for two blue (type IIb) diamond populations. Nature (2019).

  6. 6.

    Brenker, F. E. et al. Detection of a Ca-rich lithology in the Earth’s deep (> 300 km) convecting mantle. Earth Planet. Sci. Lett. 236, 579–587 (2005).

  7. 7.

    Thomson, A. R., Walter, M. J., Kohn, S. C. & Brooker, R. A. Slab melting as a barrier to deep carbon subduction. Nature 529, 76–79 (2016).

  8. 8.

    Zedgenizov, D. A., Ragozin, A. L., Kalinina, V. V. & Kagi, H. The mineralogy of Ca-rich inclusions in sublithospheric diamonds. Geochem. Int. 54, 890–900 (2016).

  9. 9.

    Bindi, L., Safonov, O. G. & Zedgenizov, D. A. Merwinite-structured phases as a potential host of alkalis in the upper mantle. Contrib. Mineral. Petrol. 170, 14 (2015).

  10. 10.

    Anzolini, C. et al. Depth of formation of super-deep diamonds: Raman barometry of CaSiO3-walstromite inclusions. Am. Mineral. 103, 69–74 (2018).

  11. 11.

    Anzolini, C. et al. Depth of formation of CaSiO3-walstromite included in super-deep diamonds. Lithos 265, 138–147 (2016).

  12. 12.

    Joswig, W., Stachel, T., Harris, J. W., Baur, W. H. & Brey, G. P. New Ca-silicate inclusions in diamonds—tracers from the lower mantle. Earth Planet. Sci. Lett. 173, 1–6 (1999).

  13. 13.

    Anzolini, C. et al. Depth of diamond formation obtained from single periclase inclusions. Geology 47, 219–222 (2019).

  14. 14.

    Smith, E. M., Shirey, S. B. & Wang, W. The very deep origin of the world’s biggest diamonds. Gems Gemol. 53, 388–403 (2018).

  15. 15.

    Hanley, P. L., Kiflawi, I. & Lang, A. R. On topographically identifiable sources of cathodoluminescence in natural diamonds. Phil. Trans. R. Soc. Lond. A 284, 329–368 (1977).

  16. 16.

    Milledge, H. J. et al. Carbon isotopic variation in spectral type II diamonds. Nature 303, 791–792 (1983).

Download references


We thank T. Stachel for constructive peer review and B. Luth for discussion on mineral stability.

Author information

E.M.S. prepared the manuscript with contributions from S.B.S., S.H.R. and F.N., and expert approval from E.S.B., J.W. and W.W. All authors were involved in this Reply.

Competing interests

The authors declare no competing interests.

Correspondence to Evan M. Smith.

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark
Fig. 1: Additional features consistent with a sublithospheric origin for the large 24.18-carat blue type IIb diamond (sample 110208093607, from the Premier kimberlite pipe at the Cullinan mine).


By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.