DIAM® & Beyond
—Innovative Beverage Closures

For more than half a century, the G3 Closure Division has served as a full range closures resource for national and international beverage suppliers. We built our reputation in the wine, spirits, and beer industries, but we also provide products and services to nonalcoholic beverage producers. As an FSSC food safety certified manufacturing company, we are committed to excellence throughout our operation.

Diam® Corks

Diam is a technological closure with a patented composition, which is manufactured from cork and treated by the patented DIAMANT process. Validated by several worldwide independent laboratories, the DIAMANT process uses super-critical CO2 to eradicate 2, 4, 6 – trichloroanisole (TCA) and 150 other compounds. Each Diam cork is guaranteed to have no TCA (below the detectable TCA ≤ 0.3 ng/l).

Ranging from Diam 2, Diam 3, Diam 5, Diam 10 to Diam 30, Diam offers a clean, consistent, sensory-neutral cork. For a more sustainable cork closure option, Origine by DIAM® is a bio-sourced cork that offers reliable, natural sealing and consistent performance with no detectable TCA. Origine by Diam® corks provide different OTR (Oxygen Transmission Rate) and OIR (Oxygen Initial Release) options to control wine aging with ranges from 5, 10 and 30 for still wines.

G3 is the exclusive distributor of the North American market. We print and finish Diam closures at the Modesto facility. Our manufacturer for Diam corks meets the world's most stringent environmental, ethical, and economic sourcing standards with Forest Stewardship Council® Chain-of-Custody (FSC® CoC) certification. Diam FSC®certified corks can be produced on request.

FSC® is an independent, non-governmental, not-for-profit organization established to promote the responsible management of the world’s forests.




diam corks

GTWIST Long-Skirt Twist Cap 30mm x 60mm

GTWIST cap collection unites the latest in wine protection liner technology with stand-out design.

We offer a wide range of GTWIST cap design options in various sizes including: Elegance Caps (top emboss and foil, top emboss and paint), Premium Caps (no knurling, smooth look), Standard Caps (custom print, stock color), G INK Technologies (Thermochromic, Bichromic, Photochromic).

Customers may choose from a wide variety of colors, sizes and printing options, and we offer both stock and customized bottle caps.



Liner Technologies


The oxygen transmission rate (OTR) controlling liner for still wine. G3 offers 5 OTRs: 3 patented liners and 2 industry standard liners.


The pressure-retaining liner for both still and carbonated wines. Liners have the same oxygen transmission rate (OTR) level as Saranex but built with a patent-pending, simple structure using less materials and PDVC/Tin-free. GFRESH liners are leak proof and offer side strike resistance to preserve your wine aroma and refreshing character over time. With G3’s extensive tests such torque, OTR, secure seal and sensory testing, the GFRESH liner can be applied with standard caps and the capping equipment.

closures liner
 closures vinotop
closures stock program


We offer Heat-shrinkable PVC, Polylaminate and Tin Wine and Champagne Capsules

view PVC fact sheet

view still wine polylaminate fact sheet

view sparkling wine polylaminate/foil fact sheet

Stock Program

Buy high-quality closures with quick and convenient service and low minimum order quantity. We offer high-quality aluminum caps, Diam corks, synthetic cork wire hoods and polylaminate capsules in a variety of options, colors and sizes. Our closures are used in still wine, beer and spirit bottles.

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Quality and
Process Control

At G3 Enterprises, our commitment to quality, the environment, and food safety includes:

  • Continuous improvement of our processes and reduction of pollution using measurable results
  • Meeting or exceeding statutory, regulatory and customer requirements
  • Involving all team members in a spirit of collaboration, ownership and accountability
  • Demonstrating our long-term commitment to the communities in which we operate; and
  • Communicating relevant food safety information within the organization and throughout the food chain.
closure quality image

Our quality checks include the following:

Incoming Process Controls
  • Dimensional and performance analysis through calibrated digital and analog measurement equipment such as:
  • Keyence Laser Profilometer
  • Keyence Instant Measurement
  • Instron Tensile and Compression
  • Torqo II Torque Tester
  • Sutherland Rub Tester
  • Egitron Medcork
  • Mecmesin Champagne Stopper Tester
  • Incoming raw cork TCA analysis through GCMS
  • Metal color standards management through robust approval process and standard library management
  • Robust Supplier Quality Management program
In-Process Process Controls
  • Statistical process controls for critical quality characteristics during the manufacturing process
  • Torque testing of caps, including automated Torqo II analysis
  • Functional line testing to simulate customer usage
  • Computerized vision inspection for artwork registration
  • Computerized vision inspection for aluminum screw cap bridges
  • Atmospheric Haloanisole testing
  • ATP swabbing of production equipment
Outgoing Process Controls
  • Sensory evaluation, including GCMS testing
  • Microbiology testing
  • Certificate of Analysis available
  • FSSC 22000, Food Safety Certification
  • Forest Stewardship Council® Certified by SCS Global Services for DIAM Corks