NDA on request
A mutual non-disclosure agreement is offered at the start of any mandate. Nothing about your identity, brief or budget is disclosed to a counterparty without your written approval.
When the stone you are looking fordoes not yet exist on the market.
MMXXVIPrague · Global
A confidential mandate to locate a single, defined piece — a particular origin, a specific colour, a precise weight — across primary cutters, auction houses and private estates worldwide. We only present when a match meets your criteria.
- NDA on request
- 14 — 30 day discovery window
- Reported only on match
- Full origin & lab documentation
Independently verified by
II
A quieter way to acquire.
Private Sourcing is not a search across an inventory. It is a mandate — a signed, single-purpose commission to locate one exceptional stone against a defined brief.
Our desk operates where the finest material moves in silence: primary cutters in Bangkok's JVC and the Chanthaburi corridor, treaty and Gulf channels through Dubai's DMCC, long-established European estates, and vetted US trade counterparties out of our Florida desk. We approach these channels on your behalf, without disclosing your identity, and we only revert when we have something worth showing.
III
A desk measured by mandates, not by traffic.
A quiet operation, sized to the mandates we accept. Every figure below is verifiable on request under NDA.
14 — 30
Days to first shortlist
Typical defined brief
5
Tier-1 laboratories
GIA · SSEF · Gübelin · IGI · HRD
4
House desks
Prague · Miami · Dubai · Bangkok
100%
Documented origin
On every principal stone released
Figures reflect combined principal experience and active mandate history. Full references available under NDA to qualified counterparties.
IVFour discrete stages.
How a mandate proceeds.
- I.Day 0
Confidential Brief
A signed brief defines the stone type, origin envelope, colour and clarity range, weight target, certification requirements and budget corridor. Executed under NDA on request.
- II.Day 1 — 30
Discovery
Our sourcing desk activates its channels — direct cutters, auction houses, private estates and trade counterparties — approaching each on your behalf without disclosing your identity.
- III.Day 14 — 30
Curated Shortlist
A short, verified shortlist is presented with full documentation — lab reports (GIA, SSEF, Gübelin, GRS as applicable), origin evidence, provenance history and confidential pricing.
- IV.On approval
Private Acquisition
Acquisition is executed against a private invoice, with secure transport, insurance in transit and — where required — bonded storage or private delivery to your appointed representative.
V
The terms of discretion.
Four commitments define how we operate a mandate. They apply from the first conversation onwards.
Reported only on match
We do not send progress updates for the sake of contact. You will hear from us when we have a verified candidate worth reviewing — not before.
Confidential invoicing
Acquisitions can be routed through private invoicing, a nominated entity or a trustee arrangement. Payment terms are agreed in advance and never renegotiated on presentation.
Documentation & origin
Every presented stone arrives with a current laboratory report, origin evidence where applicable, and — for coloured stones — a treatment disclosure signed by our house.
One brief. One accountable principal. One stone worth releasing.
The mandate ends when the stone is placed — or when the brief is honourably closed.
VII
What we source.
Two disciplines, one desk. Every mandate is executed by the same team, against the same standard of documentation.
I
Natural Gemstones
- Unheated Kashmir, Burmese & Ceylon sapphires
- Untreated Burmese, Mozambique & Madagascar rubies
- Colombian Muzo & Chivor emeralds
- Paraíba tourmaline (Brazilian & Mozambique)
- Alexandrite, spinel, tsavorite, Padparadscha
- Investment-grade tanzanite and rare collector stones
II
Certified Natural Diamonds
- D–F colour, IF–VVS clarity, triple-excellent cut
- Type IIa, Golconda-heritage and fancy colours
- GIA / IGI / HRD reports — full origin traceability
- Round brilliant, oval, emerald, radiant, cushion
- Matched pairs, layout stones and important centres
- Estate and auction-provenance certified diamonds
SD · Principal · MMXXVI50°04′ N · 14°25′ E
VIII
One name is responsible for every mandate accepted.
Martin Sosna
Founder & Principal
The sourcing desk is led by a single principal responsible for every brief accepted, every stone released, and every client relationship. There are no sub-agents, no white-labelled desks and no anonymous intermediaries between you and the mandate.
A decade and a half between the coloured-stone counters of Bangkok's JVC, the Gulf trading floors of Dubai's DMCC and the US wholesale market out of Florida shaped an approach that is deliberately narrow: fewer briefs, fully documented, fully owned.
- GIA-trained gemmologist
- ICA member — International Coloured Gemstone Association
- Rapaport RapNet authorised
- Insured, bonded and audit-ready operations
— SOSNA, MMXXVI
IX
Four desks. One accountable house.
We operate from four house desks — one per region we actually cover. We do not claim cities we do not sit in.
I
Prague
Europe HQ · advisory
House headquarters — client cabinet, final release, European advisory.
50°04′ N · 14°25′ E
II
Miami (FL)
US wholesale desk
United States wholesale, memo terms, hand-carry across the US trade calendar.
25°46′ N · 80°11′ W
III
Dubai DMCC
Gulf & Asia treaty
DMCC-registered desk for Gulf, India and greater Asia — bonded, tax-free zone.
25°04′ N · 55°08′ E
IV
Bangkok JVC
Coloured-stone lapidary
Jewelry Trade Center — direct relationships with sapphire, ruby and spinel cutters.
13°43′ N · 100°31′ E
New corridors are opened for a specific mandate, not for growth. We keep the map small on purpose.
XUnited States · Florida
Built for the United States wholesale market.
A dedicated US desk based in Florida for vetted US trade counterparties — retailers, ateliers, designers and appraisers. Terms familiar to the American trade, execution familiar to the European maison.
Miami (base)JCK Las VegasAGTA TucsonCouture
01
Florida base
US desk seated in Florida (Miami metro). Same-day domestic dispatch and secure client meetings by appointment.
02
Memo terms
Consignment memo to vetted counterparties on a per-piece basis. Standard 7 — 14 day windows, extendable by written agreement.
03
Insured hand-carry
Insured hand-carry across the US trade calendar — travel to client cities on defined show weeks and by appointment.
04
Documentation
W-9 / resale certificate accepted. Full commercial invoice, laboratory report and provenance file with every piece.
US Wholesale is a trade-only channel. Retail collectors are served through the Private Advisor.
XI
Fees & Terms — stated in advance.
One clear commercial framework. No standing retainers, no discovery invoices, no surprises on presentation.
- 01
Opening a brief
Complimentary. Opening a mandate and receiving the shortlist carries no fee.
- 02
Discovery window
14 — 30 days for a defined brief. Rarer material may extend to 60 — 120 days — communicated at brief acceptance.
- 03
Success fee
A single success fee applies only on completed acquisition. Percentage is disclosed in advance as part of the confidential pricing and never renegotiated on presentation.
- 04
Exit
You may close the brief at any point before acquisition, at no cost. The mandate ends, the brief remains confidential, and there is no charge for the discovery.
- 05
Logistics
Insured, sealed transport through vetted couriers. Hand-carry available in-region. Bonded storage on request.
- 06
Conflicts
One brief per category at a time within a client circle. No dual representation — we do not source the same stone for two competing mandates.
SOSNA Diamonds does not represent gemstones or diamonds as financial instruments and makes no promise of appreciation.
XII
Open a Confidential Brief.
The form below is the first stage of a mandate. It is treated as confidential from the moment it is submitted. Only the sourcing desk sees the content.
XIII
Where the desk is known.
The laboratories we rely on and the trade bodies we hold ourselves to.
Laboratories
GIASSEFGübelinGRSAGLIGIHRD
Memberships & standing
- ICA — International Coloured Gemstone Association
- AGTA — American Gem Trade Association
- Rapaport RapNet authorised
- Responsible Jewellery Council — application in progress
Press mentions and industry references available under NDA to qualified counterparties.
XIV
Questions our clients ask.
Is there a fee to open a brief?+
No. Opening a brief and receiving a shortlist is complimentary. A single success fee applies only on completed acquisition and is disclosed in advance as part of the confidential pricing.
How long does a typical mandate take?+
Between 14 and 30 days to first shortlist for most defined briefs. Rarer material — Kashmir sapphires, historically important diamonds, matched pairs above 5 ct — can extend to 60 — 120 days.
Do you offer viewing before acquisition?+
Yes. Private viewings can be arranged at our Prague headquarters, our Miami desk, our Dubai DMCC office or our Bangkok JVC desk. Insured secure courier to your appointed representative is available on request.
How do you handle cross-border logistics and customs?+
Sealed, insured transport through vetted couriers. Full commercial invoice, laboratory report and provenance file accompany every shipment. Bonded storage in DMCC (Dubai) is available for tax-neutral holding.
What US wholesale terms do you accept?+
W-9 and resale certificate accepted. Consignment memo to vetted counterparties on a per-piece basis, standard 7 — 14 day windows, extendable by written agreement. Same-day domestic dispatch from our Florida desk.
How is my identity protected during discovery?+
Every counterparty we approach on your behalf is engaged without disclosing your identity. NDA on request. Confidential invoicing routes — private entity, trustee, nominated representative — are agreed at brief acceptance.
What if the shortlist does not match my brief?+
You are under no obligation. The mandate ends, the brief remains confidential, and there is no charge for the discovery.
Do you deal in lab-grown material?+
No. SOSNA Diamonds sources exclusively natural gemstones and natural diamonds. Lab-grown material is outside our scope and outside our value system.